Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

97 nissan altima 2.5 runs bad-rich

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5 years 1 month ago #27185 by mobileauto
this car runs bad and sometimes stalls at stops, is smells really rich in the exhaust. I have a snap on verus, when I hook up to the obdII connector I get no communication, I can get global but nothing else. I used the nissan 2 connector and can talk to the ecm but it has very limited info, only about 10 pids and it all looks normal (fuel trims, o2 voltages, idle speed).
at the start it had several codes P0505 iac
p0135 b1s1
p0141 b1s2
p0400 and p1400 both for egr
when I clear the codes 3 come back instantly, p0135, p0141 and p0505, even tho all appears normal. the next thing is before I got this car it had a whole list of things replaced plugs, wires, fuel filter, fuel pump, intake gasket, iac motor, #4 injector and the front 02 sensor.
I spent quite abit of time with this and could find no direction.
I am hoping someone can point me in a direction of something to look at or what I am not seeing

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5 years 1 month ago #27189 by Desmond6004
So are you communicating via the 14 pin plug? I think if a Nissan of that year also has an obd plug that is most likely for the airbags or ABS system perhaps(?), while the 14 pin plug is for the ECU.
If that P0135 is coming back right away check your O2 sensors for resistance - of the 4 wires 2 should be the same colour and have a low-ish resistance like 4 - 12 ohms or something like that. Otherwise some vehicles have separate fuses for the O2 sensor heaters - check there are no blown fuses and make sure there are fuses everywhere they should be - sometimes people 'borrow' fuses from another slot when they pop their cigarette lighter fuse plugging something in wrong.

Getting involved in discussions because I have a lot to learn still.

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5 years 1 month ago #27200 by mobileauto
those 3 codes come back instantly, the front sensor has been replaced and the iac has been replaced. all fuses are there and all are good, I have not ohmed the sensors at this point, yes I am on the 14 pin connector. the o2's are responding to throttle variations but the downstream is pretty much at .5 all the time, off idle the fuel trims go negative and at idle are close to perfect

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5 years 1 month ago #27378 by mobileauto
went back today and did voltage drop on grounds and rechecked the powers. looked at each thing on the circuits and all looked good. car was idling fine during the checks, i cracked the throttle and it all went to shit. pids on the scanner still looked proper as in tps, maf, o2’s were still switching, temp was 192. and his thing acts like it’s not breathing. black out of the exhaust, it did finally die and wouldnt start pulled front sensor out for plugged exhaust and no change. it sat for about 5 min while i was doing some reading and then it starts and runs perfect. while running bad the inj ms was 9.2 way to much. did pull fuel sample and it was clear. this one where a person needs to know how mr danner thinks and thought process

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5 years 1 month ago - 5 years 1 month ago #27380 by Doc n2mx
Hi,

So what I tell my students is everything is cause and effect. Powers and grounds!

With that said I see that the o2 codes are for bad heater circuits, i would test the circuit with a test light and see if the heater circuit works. un plug the O2 and put your test light in the circuit turn on the key and it should turn on and it may flash and go off , if it does that's good you have a bad O2 . If it does not light see if you have power on one leg but use a good ground if it works you have a bad ground. if not you need to check at the PCM and test. if it works you have a bad wire going to the O2 .



Good luck
Doc
Last edit: 5 years 1 month ago by Doc n2mx.
The following user(s) said Thank You: Noah

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5 years 1 month ago #27404 by mobileauto
desmond6004 and docn2mx, thanks for your input, you both hit the problem. I went back today and figured out that when it messed up I lost power from fuse 4 after the fuse box, fuse had power on both sides but no power to either o2 heater, iac, egr sol. I jumpered 12v to the circuit thru a back probe on the egr sol and it straightened up. Long story short, after I repaired the lost power feed I ran it for over an hour with no problems. I discovered that this thing runs in open loop until you come off idle, so I am guessing this is why it would run so crappy when I cracked the throttle, thats a guess. knowing what I know now- I would attack this different than what I did. thanks again for your help and direction

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5 years 1 month ago #27425 by Tutti57
Nice find and repair!

Sent from my Moto E (4) Plus using Tapatalk

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4 years 11 months ago #28409 by mobileauto
I need to add to this saga, this car is back. it now has no codes, will start right up and idles fine, after a few minutes if you try to throttle any at all, and I do mean any it falls on its face and if you hold it there it will die but will start right back up. in the earlier post I listed all the parts that were replaced before I got this car, I am the 3 and now 4th to work on it.
when you cant throttle it the maf if fixed at 1.6 mv and both o2 sensors are at 30mv and stuck there, this does idle in open loop by design. I can unplug the maf and instantly it will throttle fine until about half throttle and it acts like a rev limiter-hook the maf back up and it runs perfect just like it is supposed to for a time then the same thing all over again. the maf is a new, not reman, delphi unit.
I have checked the ground on the maf along with the 12v source and signal, it all looks fine, sorry for the long post but I need some direction, feeling really stupid at this point.
thanks for any help and direction

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4 years 11 months ago #28423 by rpd1125
If the throttle blade was moved in anyway with the key on when you worked on it or when someone else did. You will need to complete the following relearn procedures. Nissan throttle bodies are so sensitive. So at the very least the pedal and Throttle relearn must be completed


Nissan Throttle Body Relearn Procedure
1) Perform the Accelerator Pedal Released Learning procedure. This procedure tells the ECU what voltages to expect when your foot is off the pedal

Foot is off the accelerator pedal
Turn ignition switch ON and wait at least 2 seconds
Turn ignition switch OFF and wait at least 10 seconds
Turn ignition switch ON and wait at least 2 seconds
Turn ignition switch OFF and wait at least 10 seconds.

2) Perform the Throttle Valve Closed Position Learning Procedure
Foot off the accelerator pedal
Turn ignition switch ON.
Turn ignition switch OFF and wait at least 10 seconds
During the last 10-second period, listen to the throttle body to make sure you hear it moving.

3) Start the engine and let it run under the temp gauge is in the normal range.
4) Turn ignition switch OFF and wait at least 10 seconds.
5) With your foot off the accelerator pedal, turn the ignition switch ON and wait 3 seconds.

6) Then perform this procedure with the engine off, key in ON position.
Repeat the following procedure quickly five times within 5 seconds.
Fully depress the accelerator pedal
Fully release the accelerator pedal.

7) Wait 7 seconds, fully depress the accelerator pedal and keep it down for approx. 20 seconds until the MIL stops blinking and turned ON.
8) Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
9) Start engine and let it idle.
10) Wait 20 seconds.
11) Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.
Idle speed = 650 ± 50 rpm (in P or N position)

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4 years 11 months ago #28424 by Tyler
Did you happen to do your MAF voltage checks while the MAF PID on the scanner was showing 1.6mV? If not, get your multimeter on the MAF signal wire and your scanner watching the MAF PID. When the PID drops out, see what the multimeter says.

If it's reading a rational value (usually, around 1.5V at idle for Nissan), then there's an open in the signal wire somewhere. If it agrees with the data PID, either the MAF is failing, signal wire is shorting or there's a power/ground problem to the MAF.

Either way, you may be disturbing whatever the problem is by unplugging the MAF.

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4 years 11 months ago #28444 by mobileauto
this is a throttle cable engine

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4 years 11 months ago #28445 by mobileauto
I got the voltage from the scanner pid, I did use the scope to watch signal to see what it looked like, the voltage doesnt drop out it just fixes at 1.6 and wont move as do the o2's at 30mv. you may be right in the fact that the maf may be the problem but I havent been able to prove it

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4 years 11 months ago #28525 by mobileauto
ok, I got back to this car today, it ran fine until it warmed up some then the maf fixed at 1.11, alittle higher today. could not throttle it at all. Had the scope on the maf signal, and I did check the voltage and ground again. when it fixed the scanner and scope matched and maf signal was flat lined at 1.11. I did have another used maf to try on it so with the engine temp up and it was messed up, I shut it off, changed the maf, started it right back up and the maf signal came alive and car ran fine. it did have a bit of a rough idle but at least you could throttle it and the signal looked good on the scope. if this ends up fixing it the "new" delphi sensor had a problem and the used one did not, lol

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