89 Chevy Silverado issues.

That actron 9690 doesn’t look to bad for about $250 on flebay. The only thing you would be missing is the bidirectional to manually actuate things from the tool, but you can certainly get by without it.

I checked the timing with the engine running, the pointer is moving back and forth abt 1/2 inch. I tested the MAP, the signal voltage is all over the place, fluctuating from 0.88 vdc to 2.55 vdc. its fluctuating so fast, you can hardly read the numbers. it has the 5 volt refrence on the other wire, and a good path to ground on the remaining wire. I removed the map sensor to get a good look at it. the backside looks like it has melted sone in the corner. I dont know if this is from an internal problem or if it was heat from the outside near the engine. it sits on a bracket well off of the engine.. im thinking the MAp is the culprit. I would think that the timing moving around is due to the map being bad and the ignition module is just doing what its signaled to do when the map signals it.
Im going to get a new sensor tommorow and see if that fixes it. the sensor should not have a hot melt spot on it, and I dont think the voltage should be fluctuating that fast or that much. probably 5 different values a second. like a confused calculator.

im afraid to swap parts off my other truck because of experiences ive had in my life. heres one example.. I pulled and cleaned A tough old german ladys window A/C. she kept telling me she was worried abt the water.. ad nausium,. finally we got the A/C back into the window, and the exact moment I plugged the A/C in, everything in the house went out.., She started screaming, you ruined my electric, you ruined my vires, you ruined my house!!!! So I went to the breaker box, and nothing was tripped. went in the backyard, to see if meter was running, nothing. so I went in the front to go see if her neighbor had power, when I spotted the big TU Electric truck. they had cut the power to change a transformer.
so I dont want to mess with my other truck and something fail, just as I happened to pull it off, then im out there really sweating it, because that is my fishing truck.

im going to read the online manual for the 9690 and see what all it does. I think in maybe a year or 2 I will have learned enough to be able to use it with good results. im still learning how fuel trims work, and emissions but the big picture is starting to form. Ive learned alot watching danners vids, and a guy called southwest main auto repair, dans brother, and eric the car guy, and yourself, and im appreciative.
If I could find a vid on how exactly the gm computer sequence of operation works, I would get alot out of it. I understand the gm bypass ignition system, its the fuel mapping I would like to know intimately. like what EXACTLY is happening when its surging, is the map reference sensor out of tolerance and the computers sees this and tries to default the fuel trims back to a preset parameter or does it just ingore the errant signal and depend on the coolant temp sensor, and or tps signal.. basically what is going on in the ecm.

Congratulations, I knew you’d find it. I know exactly what you mean on the Murphy’s law and apparently the old German lady did too. I’d also have to pass any thanks on to Paul as well. On the fuel mapping and what the ecm is thinking start at MOATES.NET and poke around and then EFI LIVE. I think you’ll find them interesting.
Also, I’m not positive, but I think the voltage swing max to min should only be about 1.5v on these map’s. If you had something like a mityvac hand pump to apply a steady 19 or 20” of vac, you could remove the variable of fluctuating engine vac. For future reference.

will get a map sensor probably tommorow and pray that fixes it,, the way the signal was jumping gives me great confidence that the map is bad. what is the square black box with the 5 pin connector that mounts right next to the map sensor. it doesnt have anything but a connector plug, no vacuum.

yes I appreciate everyone who contributed. Im going to really enjoy not hearing the truck surge,. Im still teaching my son how to drive standard, so if it is running good, it will be easier. we bought it for 600 and probably put abt 800 in parts in it. probably 60 hours of labor. Im going to give my son the option to buy me out, if he doesnt want it, we will sell it. I hope he keeps it, we spent alot of hours together working on it, and he learned alot. if we do sell it somebodys going to get a good rust free truck, with a lot of new parts. everything works. the only downside is it has no a/c system. were going to put new tires on it soon. the tires will pass inspection but they are worn. headliner is gone. seat is worn, windshield has a chip.. abt
what would be expected for an old truck.
we have replaced battery, ignition switch, radiator, water pump, belt , pulleys, fan, hoses , t stat, brakes and hardware, differential fluid, topped of transfer case fluid, replaced worn sway arm bushings in front, had heads decked and valves worked, complete top end gasket set, new o2 sensor, new tps sensor coming, new cap and rotor, ingnition module replaced and distributor refubished, fuel filter removed and cleaned. new washable air filter. the only thing it needs left to pass inspection is the exhaust pipe needs to be extended to the outside of the bumper. all 4 headlights and tailight lenses were replaced before we got the truck. wish he had replaced the casette player,, haha

He should definitely keep it,a spare vehicle or just don’t want to take that fourth friend with you. His toys are gonna get bigger and need to get them home. That little square 5pin box should be the knock sensor module. I can’t remember exactly what they call it. It sends its info to the computer to aid in the spark timing.

did some research and the map does control fuel and spark, so I see why the ignition is moving around. would also explain the occasional backfire. the engine is a confused mess..... signal jumping around, idle jumping around. if the map controls timing and fuel, I wonder how it interacts with the TPS. THE TPS is also sending a signal voltage to the ECM. Im thinking that once engine is off idle the tps may take over the fuel parameters and the MAP sends signal to the ecm to advance timing thru ignition module.. just a guess. but they both cant be controlling fuel and timing> these years dont have crank or camshaft ref sensors.

gonna send jr to the parts house after while. and get a MAP SENSOR. will confirm if it fixes it.

yes he has a little honda civic my bro in law gave him, but every man needs a truck. he could go pick dates up in it. some chicks like old trucks, that raw rumble , smell of burnt oil, they are roomy and manly trucks. that bench seat is good for hugging too. she caint be too fat though, if she is blocking the stick shift, you have to ride around in one gear. My wifes always trying to make excuses to drive my 94.. I tell her she cant handle the silverado,,, too much power. I keep my boat hooked to my 94. If I unhook it and bring it in the front, she will hop in that son of a gone and go. Like its a strong . loud wild horse shes wanting to ride ha it is loud dual exhaust, and puff a plume of smoke on start up, (lworn valve stem seals). love to see people reaction when at gas station and they are behind me, the hear VRROOOO, then the bluish black cloud drifts over thier car,, ha
My 94 runs super, and shifts like dream .

I ve heard the 95 1500s are problematic, my transmission mechanic told me they tried to make some changes that year that fell flat. not sure what else they did, with the engines and so on, but many people shy away from the 95 model year.

waiting on jr to bring the MAP sensor from the parts house, went out and took another voltage reading from the signal wire on the MAP, The air is cold and damp here today, the voltage is now fluctuating between 1.66 and almost 3 volts dc. when the voltage gets around 1.55 it is running ok, then the higher the voltage goes the lower the idle to almost shut down. its not a constant, duplicate surge today, its more of a high idle, less prominent surge, but easily heard.
Im thinking that some of the reason for changes in the way the truck runs may be due to when the truck is shut off, the computer resets to a base parameter, and then starts trying to compensate to a happy spot, or in my case compensate for a faulty sensor and incorrect voltage signal .

The computer uses the map for baro reading at key on and Wot. So if you’re climbing a mountain and it starts running crappy mash on it or pull over and key off. I would guess the map has priority but the computer is an if this than that device, meaning if I’m seeing this, than do that. Paul’s got a good video on it somewhere. For each voltage of each sensor there’s a programmed injector pulse width. The 95’ was the cross over year for obd2.some came with obd1 connectors some with 2 , but still read as obd1 and monitored more stuff. My 93’ had the electronic 4l60 already but not sure what they made for changes internally if any. I do know my 97’ burb has the newer 4L80e and it did have physical changes in those years. But you can always dummie them up with a carb and external trans controller.

the 8im working on is the 4 speed standard wIth OD . MY 94 has the 4L60E and when it was rebuilt, all of the weak parts were replaced, with improved heavy duty stuff. aluminum instead of plastic pistons, heavy duty OD CAGE, 5 gear pinion sprag , raybestos frictions. rebuilt valve body. new wiring harness. all new electricals , new converter, shift kit. I have a damned good tranny man. he explained to me, that the most important thing is hydraulic pressure integrity. many guy put the super duper red eagle alto frictions and a bunch of other stuff like high performance fluids, additives, ect, but all of that wont do any good if there is a pressure rise malfunction.. the clutches can only clamp as hard as the hydraulics make them, and if the valve body is worn, or the pump or gaskets, the new stuff will not last. He told me he could take a transmission that had worn bands and clutches, and put in a rebuilt pump, new seals and gaskets and valve body, and it would still last a very long time. the valves in the valve bodys can oscillate millions of times in a vehicle with 100.000 miles. when the circuits wear, they leak. same with the check balls, they spin, and can get flat spots in them and leak. the electrical solenoids cycle alot too, they can check good electrically but the pintles can wear and malfunction. Most shops dont rebuild transmissions, they put in the parts they think will fix it and hope for the best. actually rebuilding a transmission is quite extensive. removing and replacing all of the bushings is important too. the guy I have is like a transmission savant. if you met him on the street, you would think he couldnt walk and chew gum, but looks can be decieving. he works out of an old carridge barn from the 1900s , just an old shed, but he is one of the best transmission men in tx. im going to have him do the A500 in my dodge ram im pulling the motor and buying a rebuilt long block for it, . I have 5 trucks. an 89 dodge dakota shelby (only 1500 made), runs but needs trans rebuilt have owned it since 1993, . a 98 dodge ram, bought from my uncle because his floor in his house was rotten, and he didnt have any money to fix it, spun bearing, and transmission worn out has the 6 cylinder good for 300,000 miles if taken care of, )it wasnt)l ,. we did body work and painted it, so its next,, my 94 k1500, and wifes 05 nissan frontier. and of course the 89 scottsdale long bed.

anyway kif u ever go to get a transmission rebuilt, ask them whats the most important aspect of a transmission, if they dont say hydraulic pressure integrity,, RUN..

Map sensor has arrived, gone put it in right na.

whats Pauls you tube name or link,. thanks

Ok immediately after replacing the MAP; with a 50 .oo duralast the truck started idling great,, first slightly high idle then down to normal. took truck for a ride and check engine light came on. it threw a code 43. we drove home and took the air filter housing off and I noticed one if the pink wires going to the ignition coil was stretched tight over the EGR valve, possibly pulling on the connector and making a bad connection to the coil, we strapped the wire tight to the fuel line, after pulling some slack so it isnt pulling on the connector anymore. Im going to reset the computer and try starting the truck, it had a bit of a miss while driving and reviing at idle.
This truck has grabbed hold of me like a pit bull on a chihuahua. It simply refuses to leave me alone, like its been neglected so long, and it has somebody who is trying to fix it right, and it has attached itself to me, like a barnacle.
Its like every time I fix something, another issue pops up, like the truck has a gig list its feeding me.

Why did nt it throw a code 43 ev er before I replaced the MAP sensor, maybe the ECM is trying to relearn the sensors? I will disconnect the battery for a few minutes then try again. seems like it was very sluggish running around the block, like the timing is maybe stuck in base mode and not advancing. Yet before with a bad MAP sensor, it would surge at idle but run strong thru the gears. CRAZY...

ok after replacing the MAP sensor, it starts and idles fine cold, and after it starts to warm up, it goes into a steadily declining surge. not as pronounced as before. I looked under the truck and there is a sensor in front of the starter with no wire going to it, but on the opposite side, in the block up from the oil filter there is a sensor . I dont know if the truck had 2 knock sensors, or this is a different sensor.. there is a oil pressure switch with a cone around it near the oil filter, so I dont think it is an oil pressure switch.
the truck isnt throwing the code 43 right away, as I understand it does a test on every start cycle. I erased codes, ran it for abt a minute then rechecked for codes, it was clear. then I started it again and let it run. it seems like the idle surging got progressively worse. I read that the computer will keep either retarding or advancing the timing in 1 degree increments to attempt and cause an engine knock. so im thinking this could be the issue. I can take pics of the sensors in speaking of if needed. it looks like the wire going to the sensor on the opposite side of the block, was spliced in. it is seems it was done by someone who at least knows what shrink tubing is. so folks, it seems we have another scooby do mystery to solve. as I said my oil pressure sensor is near the oil filter, not near the distributor as many seem to be. the sensor in the block had to be for something but there is no wire that goes to it, or a wire nearby that isnt plugged in,, the sensor in the opposite side of the block from the sensor in front of the starter looks a bit different., it does have a large black rubber connector plug on it,.

when we bought the truck the ignition control relay was in a bucket along with other parts. it was on the bracket, but there was no MAP sensor with it. so that is what we had plugged in when it idled good. when we went to the junkyard to find out what part the green connector plug went to , we got the whole bracket with the Ignition control relay and MAP sensor on it. it seems like that is around when it didnt want to idle right anymore. so tommorow in going to put the Ignition control relay that was on it before, along with the new MAP sensor and see what it does.
attached is the part im speaking of. possibly the circuitry in it is different, I didnt pay attention to what year truck it came off of.
I tell ya I will never by a truck again where half the engine and electronics are missing and the other half have been installed in the wrong locations.
this is getting ridiculous,, the only reason I think there would be a second knock sensor is maybe they couldnt get the original one out, and removed a block drain, installed it on the other side, and spliced an extension wire to reach. they are only supposed to be torrqued to 14 ft pounds,. shouldnt be stuck in there.