Electric Throttle Body Failures Without Codes?

So just wondering people's experiences with electric throttle bodies. Has anyone ever experience them intermittently glitch without setting a code? Or even how are they for intermittent issues? Or are they more prone to have a constant problem when they fail?

The vehicle that made me wonder this was a 2006 Dodge Ram 1500 with the 5.7L hemi. We replaced the transmission solenoid pack on it. We've done so many of them on these Dodges.... Anyways, going for a test drive after the repair the vehicle didn't feel like it was running 100%. It was pretty subtle but you could definitely see it on the data. Truck would be driving normal then fuel trims would jump hard positive then hard negative then normal. Likewise the O2's would be burried lean then jump to high rich then back to normal. Whole process would last for about 2 seconds.

That's all I had a chance to do though. The main repair was done. I told the boss that it has an engine issue lurking. He drove it and said it felt fine and gave it back to the customer. A couple days later the boss told me the customer said it had stalled on him a couple times and sometimes surges when stopped at a light.

So when going through possibilities of what could cause similar symptoms I wondered about the electric throttle body. But then there's no codes and I haven't seen enough failures to draw any conclusions. Does the absence of codes drop the throttle body way down the list of suspects? Or does it not necessarily affect the likelihood of a throttle body problem?

I'm not trying to condemn the throttle body. I haven't done any actual diagnosing on this truck yet. Just trying to get a feel on the throttle body and where to put it on the list of priorities.

Interesting issue... I personally have never seen a throttle body problem that didn't come with codes. Not counting cases of coking or carbon buildup at the throttle plate itself.

I personally would put the throttle closer to the bottom of the list, especially since I've never had any problems with a Chrysler throttle body. BUT, everyone's experiences are different! Let us know where this one ends up?

A scope would be handy here, what you want to do is test the signal wire. the other two are your power (5v) and ground. so is not hard to pick apart. you are going to want to move there throttle looking for spikes the voltage of the signal

Is there any chance it's still a transmission issue? Sounds a little like a converter lock up issue. (Not sure if the fuel trim fits this theory).
Hopefully when you get it back it will have some codes. I'd like to see how this one plays out if you get the chance to get back under the hood.

And to answer your questions, on the Ford and GM products i've seen with throttle body issues, there's always been some kind of code.

Ah, k. That's kinda what I thought. I knew APP's were pretty solid for throwing codes on failures with two to three separate circuits through the pedal so I figured throttle bodies had to be similar.

This one's not a transmission issue. Mostly it happens when first coming to a stop. The test drive was in city traffic with frequent turns and stops. The trans wouldn't have had a chance to apply the TCC. When it acted up it was very subtle. Only about a 50-100 RPM drop and no major change to MAP readings but HUGE change to o2s.

I'll post a followup if/when the vehicle comes back but I have no idea when that will be. Could be a while even. I did save the PID data from my drive. Will post that in a minute.

So here's the PID data from my test drive. Of course going over it after the fact I can't help but think of all the PIDS I wish I could have set for the drive. I totally forgot to set vehicle speed. A few others would have been nice too. I guess that's why they call it hindsight...

Here are some O2 highlights. I didn't like how I didn't see much change in any of the MAP Vacuum, RPM, or TPS readings when the O2's burred rich or lean.

354 - 384 - O2's stuck lean
473 - 590 - O2's stuck lean
590- 692 - O2's very rich
1076 - 1128 - O2's very rich
1896 - 1972 - O2's very rich
2000 - 2156 - O2's stuck lean
2200 - 2330 - O2's very rich
2484 - 2650 - O2's stuck lean
2702 - 2860 - O2's very rich

... etc ...

There were also some moments with very low MAP Vacuum yet TPS and RPM didn't seem high enough to match.

1464
1606 - 1632
1804
4856 - 4950
5276
5344 - 5380
5556 - 5579
6770 - 6788
6847 - 6872


To be clear this vehicle had a lot of power. I could easily light the tires. Most of the drive was light - medium throttle on flat roads with an empty truck. I didn't beat on it. The only real kinda snaps were at 6495 and 6577. Both times the RPM jumped high in a very short time but both times throttle blade position said only 14%...

And then there's 6780. 6780's the only time where throttle showed above 40%. I don't like that it's saying next to 0inHg of manifold vacuum... I would have only been going about 20mph when I hit the throttle here. If it truly were WOT I would have expected the RPM to jump higher and faster...

And lastly 5350 - 5380... That entire stretch is showing next to no manifold vacuum yet throttle angle of only 35%..?? Plus a slow RPM climb..? Again flat stretch of road with nothing in the truck...


That's really all I got a chance to grab off of this truck as it went back to the customer. Just enough to know that the truck didn't feel quite right and the data looked rather odd.

ecwurban wrote: So here's the PID data from my test drive. Of course going over it after the fact I can't help but think of all the PIDS I wish I could have set for the drive. I totally forgot to set vehicle speed. A few others would have been nice too. I guess that's why they call it hindsight...

Here are some O2 highlights. I didn't like how I didn't see much change in any of the MAP Vacuum, RPM, or TPS readings when the O2's burred rich or lean.

354 - 384 - O2's stuck lean
473 - 590 - O2's stuck lean
590- 692 - O2's very rich
1076 - 1128 - O2's very rich
1896 - 1972 - O2's very rich
2000 - 2156 - O2's stuck lean
2200 - 2330 - O2's very rich
2484 - 2650 - O2's stuck lean
2702 - 2860 - O2's very rich

... etc ...

There were also some moments with very low MAP Vacuum yet TPS and RPM didn't seem high enough to match.

1464
1606 - 1632
1804
4856 - 4950
5276
5344 - 5380
5556 - 5579
6770 - 6788
6847 - 6872


To be clear this vehicle had a lot of power. I could easily light the tires. Most of the drive was light - medium throttle on flat roads with an empty truck. I didn't beat on it. The only real kinda snaps were at 6495 and 6577. Both times the RPM jumped high in a very short time but both times throttle blade position said only 14%...

And then there's 6780. 6780's the only time where throttle showed above 40%. I don't like that it's saying next to 0inHg of manifold vacuum... I would have only been going about 20mph when I hit the throttle here. If it truly were WOT I would have expected the RPM to jump higher and faster...

And lastly 5350 - 5380... That entire stretch is showing next to no manifold vacuum yet throttle angle of only 35%..?? Plus a slow RPM climb..? Again flat stretch of road with nothing in the truck...


That's really all I got a chance to grab off of this truck as it went back to the customer. Just enough to know that the truck didn't feel quite right and the data looked rather odd.

File Attachment:

File Name: 2006DodgeR...7.25.zip
File Size:309 KB

Not sure what I am looking at with your data list.
Did you replace the upstream O2 sensors along with your transmission repair? If you did, you cannot use anything other than an NTK sensor in these.
Do me a favor and make sure you have a good heater positive circuit for these O2s as well.

Duh, I missed the file attachment

Haha ya I've been totally having one of kinda days... The data is just in case anyone is interested. I'm not putting much effort into it. It's just a capture I did after replacing the transmission solenoid pack. On the drive I noticed a few anomalies and noted it to the boss and the owner. I didn't get a chance to do any real diagnosing on the engine. It just got me thinking about electric throttle bodies in general and wondering if they're much of a variable to consider or if they're pretty much always accompanied by a code.

Thats kind of weird. The throttle blade position does seen to remain pretty low regardless of what RPM range you're in.
What's up with these o2 sensors at 2 and 3 volts? Some AFR wideband thing I don't understand yet?

This is a narrowband O2. Some just use a steady bias voltage. I think it's just used for error detection purposes. I'm pretty sure on these guys if you go to global OBD2 mode it'll show the values scaled to a normal 0-1v range.

Yeah, I can see where the O2's start 'wandering' around frame 2000 :huh: Almost wondering if the PCM was doing some O2 monitor testing, looking for reaction times? Just a guess. I'd go for one upstream O2 going lazy intermittently, but not both.

Looking just after frame 1600, the throttle opens to around 30%, but the MAP goes atmospheric. I initially thought about the EGR opening as commanded, but that seems like a lot of EGR flow for a relatively low vehicle speed.

I love thinking about anomalies I encountered earlier and trying to figure out if I can learn how to interpret them or at least learn how to get useful information out of them. For me, the coolest thing is looking at something, such as some data or waveforms, and immediately knowing where to look for the cause. Anytime you have a vehicle in front of you that you know would take most shops tons of hours and huge dollars in test parts to try and find the problem yet you were able to just look at a picture and know exactly where to go... That's the best feeling in this trade by far. For me at least haha. That's totally what keeps me going putting in all of the after hours research...

I was totally kicking myself for not putting in any EGR PIDs. I think this vehicle even has an EGR Error PID. Although I thought that would have triggered a code if it were an issue. I thought the EGR position sensors in these guys were really good at throwing codes on errors..?

I hear you about the O2s possibly lazy. They both reacted pretty much identically which would seem rather unlikely if they were lazy. I wondered if it might be some kind of test or the PCM trying to compensate for something. It almost seemed a little too perfectly lean and rich to be caused by something other than an attempted compensation...

Again, I'm not terribly concerned. I just always like to try and learn new techniques and ways of interpreting data that might potentially be of use in the future

ecwurban wrote: I love thinking about anomalies I encountered earlier and trying to figure out if I can learn how to interpret them or at least learn how to get useful information out of them. For me, the coolest thing is looking at something, such as some data or waveforms, and immediately knowing where to look for the cause. Anytime you have a vehicle in front of you that you know would take most shops tons of hours and huge dollars in test parts to try and find the problem yet you were able to just look at a picture and know exactly where to go... That's the best feeling in this trade by far. For me at least haha. That's totally what keeps me going putting in all of the after hours research...

Truth! For me, the diagnosis is way more rewarding than the repair. Fixing stuff is fun, too, don't get me wrong, but troubleshooting is the real challenge.

I was totally kicking myself for not putting in any EGR PIDs. I think this vehicle even has an EGR Error PID. Although I thought that would have triggered a code if it were an issue. I thought the EGR position sensors in these guys were really good at throwing codes on errors..?

Totally agree, I think the PCM would have caught a misbehaving EGR. I was mostly thinking about the EGR opening under normal operation, but that would seem like a really aggressive EGR strategy? No VVT on this engine, either.

Amazingly enough this vehicle finally came back. Apparently it's stalling on them fairly regularly. I had it stall on me once. Was driving in a parking lot barely moving, came to a stop for half a second then let off the brake to creep forward and it died. One minor stumble then just off. There's nothing obviously wrong that would cause that but it does also have a few minor issues. I don't think they're causing the truck to suddenly stall but they need to be done anyways and maybe I'll find something along the way.

One thing I noticed is one of the coils had a bad boot. That was actually really cool because I found that out just by looking at some PIDS while sitting in the driver's seat. This is a 2006 Dodge 1500 with the 5.7L. In the engine data there is an ignition menu. It monitors the coils and has PIDS for each coil's dwell time as well as spark burn time. That's pretty cool! Right away I could see the number 6 coil had a problem. All coils had the same dwell time and all but the #6 had around 2.2ms burn time but the #6 was 0.2ms. I'm sure that's not as accurate as scoping the secondary patterns yourself but that's pretty cool nonetheless! I pulled the coil and plugs out. Plugs were alright but there was a lot of corrosion between the boots and the coil.

The vehicle's also throwing a P1521 - Incorrect Engine Oil Type. Apparently it monitors engine oil pressure and temperature, coolant temperature and a bunch of others and is able to determine if the viscosity is right. The last oil change was done at a quick lube place 3000 miles ago. Vehicle calls for 5w20 and the sticker says Pennzoil 5w20 synthetic. Now just because the sticker says that doesn't necessarily mean that's actually what's in there... So who knows...? Supposedly these engines are super sensitive to the right oil. They don't have VVT but it does have the multi displacement system. Going to change the oil tomorrow. But there's also a TSB for this code. Apparently they were susceptible to flagging this code when there is no problem and there's a flash update to correct that. I'll see tomorrow if the fresh and correct oil makes any difference.

Out of curiosity is this engine gdi? To be honest I've not had to study one yet but all the literature I've read about gdi throttles is that they're not directly related to engine speed or load like they have been in the past. Just adding to the conversation.
Might make a point of recording some in the near future and posting them.

ecwurban wrote: One thing I noticed is one of the coils had a bad boot. That was actually really cool because I found that out just by looking at some PIDS while sitting in the driver's seat. This is a 2006 Dodge 1500 with the 5.7L. In the engine data there is an ignition menu. It monitors the coils and has PIDS for each coil's dwell time as well as spark burn time. That's pretty cool! Right away I could see the number 6 coil had a problem. All coils had the same dwell time and all but the #6 had around 2.2ms burn time but the #6 was 0.2ms. I'm sure that's not as accurate as scoping the secondary patterns yourself but that's pretty cool nonetheless! I pulled the coil and plugs out. Plugs were alright but there was a lot of corrosion between the boots and the coil.

This is really cool stuff! Always happy to find it when doing diagnostics. I find that Ford also provides this on some of their V6 waste spark systems, and on some of their newer COPs.

I'm also not positive exactly how accurate the scan data is, but I'm pretty sure it's measured from the primary voltage waveform at the PCM. It's accurate enough for me to use as a direction tool, anyway, but maybe not enough to sell ignition parts directly

Tyler wrote: I'm also not positive exactly how accurate the scan data is, but I'm pretty sure it's measured from the primary voltage waveform at the PCM. It's accurate enough for me to use as a direction tool, anyway, but maybe not enough to sell ignition parts directly

Oh ya for sure. I wouldn't sell directly off it. But it was a sweet find. The dwell PID was the same as all the other coils so, theoretically, the control side is fine. But the burn time PID was only 10% that of the others. Sure there's always the possibility of a primary issue but my money went on excess resistance on the secondary side. The kind that would be obvious on an inspection. So after only 30 seconds of looking at data I knew exactly where a problem was and what kind of problem it was. Didn't even bother for any scope captures. Just went straight to yanking out the coil and plugs and sure enough one of the boots was all mangled from heat and they had tons of corrosion between the boots and the coil.

Of course that wasn't the main problem but that was a problem. One that might have been difficult to find otherwise. Most of the time it just felt like a partial burn. Plus it was one of the cylinders that gets deactivated so you wouldn't feel it at all under a cruise.

So for an update on this vehicle. There are many things I don't like.

1) Fuel trims

When you start it you almost always see about +13% long term on both banks. Short term for both banks will be roughly negative that amount. Giving you a net trim of close to zero. As it warms up it goes more towards the lean side. Especially at idle. When you rev it it gets a little better but not totally better like a vacuum leak. We've sprayed this thing up and down many many times and couldn't find any leaks.

I'd love to be able to do an injector balance test on this but I don't have one of those manual pulsers and Dodge doesn't provide it as a bi directional test. It's at 150,000 miles so it's quite reasonable to assume the injectors could use a cleaning. Especially for injectors on cylinders that get deactivated. I can't imagine that to be great for their nozzles... Being closed while still being exposed to heat from the active cylinders.


2) Throttle Position PID

Wide open throttle run won't go above 70%. I don't like that but then I don't like that there's no code for it. How do you diagnose that? Is that a problem or is that the computer saying, "Hey, I know you have the foot all the way down but I don't want to open this any more than 70% because you're not under load and don't need anymore than 70%" Hmm...


3) Oxygen Sensors

I HATE everything about these buggers. They're choppy, they go lean for obscene amounts of time then they'll go rich for long times. But again, there are no codes. I think they could use a good cleaning. I'm starting to think all of that lean/rich business is the computer freaking out and doing major cat efficiency tests. I wouldn't be surprised if the cats are on the way out. How do you draw the line of what to diagnose?? Sure I could do an oxygen storage test myself but then I'd be spending a bunch of time just to find out if the oxygen sensor data is indicative of a problem and I can use it or if they're intentionally that way and ignore the data. In so far as to say that it'll need cats in the future but for now that data's not going to help you find the problem you're tasked to find.


Conclusion:

This truck has problems. The customer is concerned about stalling. None of these issues would cause sudden stall conditions when the truck otherwise runs good. So I have to move on and ignore all that junk.


Eureka:

This truck finally started stalling on me! :woohoo: One of the hardest skills to develop is the ability to recreate problems. That's why my boss is terrible for sensing problems. :huh: Whenever he test drives something it's straight to drive-it-like-you-stole-it mode. Sure that'll find some problems but if you want to find a problem that a customer is complaining about you have to drive it like how they would...

The problem's with the tranny. I knew the tranny wasn't great. It doesn't like creeping. At times it'll lurch a bit when warm. But she shifts like a dream. Kicks down fine, will peel tires, no slipping, no delayed engagement, etc. We did the solenoid pack on it a couple months back. The customer tends to put things off. I know they would have driven on the faulty solenoid pack far longer than they should have. The valve bodies on these 545RFE trannies are incredibly simple. It's just a one part unit with little more than a few spool valves. Everything else is controlled by a large, contained electronic unit that bolts on top. It's non serviceable and gets replaced as a unit. This unit handles pretty much all control and hydraulic functions of the transmission. It was a new unit so, aside from the possibility of a faulty part, the control side of this transmission should be fine. Fluid is new and at correct level. So the problem should just be with the mechanical side.

To make the truck stall you need to lightly cruise for a couple minutes at 35+ mph. No load, even throttle in 3rd of 4th. Then come to a sudden stop. Don't lock the brakes but come to an abrupt stop and stay there. After about a second it feels like the engine is being dragged down. The longer you cruise and the shorter you stop the more likely it'll stall. It very much feels like a torque converter issue. If you do this procedure and shift into neutral right as you stop then it'll be totally fine. The TCC solenoid is in that solenoid unit that was replaced. They're normally very good at detecting problems and setting codes if it's purely a solenoid issue.

So I think this truck is finally licked. Chances are we'll just be throwing a torque converter in it.

ecwurban wrote: Oh ya for sure. I wouldn't sell directly off it. But it was a sweet find. The dwell PID was the same as all the other coils so, theoretically, the control side is fine. But the burn time PID was only 10% that of the others. Sure there's always the possibility of a primary issue but my money went on excess resistance on the secondary side. The kind that would be obvious on an inspection. So after only 30 seconds of looking at data I knew exactly where a problem was and what kind of problem it was. Didn't even bother for any scope captures. Just went straight to yanking out the coil and plugs and sure enough one of the boots was all mangled from heat and they had tons of corrosion between the boots and the coil.

Of course that wasn't the main problem but that was a problem. One that might have been difficult to find otherwise. Most of the time it just felt like a partial burn. Plus it was one of the cylinders that gets deactivated so you wouldn't feel it at all under a cruise.

Agreed, this is how I usually go about misfire diagnostics with scan data burn times. It probably goes without saying, but you'll also find Jeeps with the 3.7 and 4.7L engines have the same data available. Came in handy diagnosing a blown head gasket recently - the cylinder that was blown had way shorter burn times than the others.

Overall, I think it sounds like you've done a great job on this truck Staying focused on the customers complaint, and applying logic to the various other symptoms you've found. My go-to saying for stuff like this is, "_____ might be A problem, but it's not THE problem."

3) Oxygen Sensors

I HATE everything about these buggers. They're choppy, they go lean for obscene amounts of time then they'll go rich for long times. But again, there are no codes.

:lol: I've noticed the same thing! I think newer Chrysler products tend to use a very 'aggressive' O2 strategy. They'll work the short term trims really hard to get an O2 signal switch, and end up 'chasing their tail' in a way. Other makes aren't quite such slaves to their O2's.