Black88Z

Alright, Im having trouble with my '88 350tpi. Heres whats going on with the car:

It has loads of power and runs grerat when cold, but the more it warms up the worse it gets. The idle will stay normal, sink a little, then rise back to normal, no big deal. the main problem is that it will start missing,bogging down, choking/flooding and stalling. Its backfired through the exhaust a couple times. Whats strange is sometimes when warm itll run poorly, missing and bogging down when given gas, but sometimes it wont in park or neutral. only in gear it will do it. But other times it doesnt matter. I dont know why this is.

This morning when i started it it ran for about 3 seconds, then died. i started it back up, died a few seconds later. pushed the pedal in 2ce and started it, kept running. backed it out and it died in reverse. Each time it cranked a little more than usual. started it back up AGAIN and it started up great, and when i put it in drive it came back stronger than ever! It was very strange.

a few hrs later i unplugged the MAF and started it, it seemed to run AND idle a bit better. i never put it in gear, but it ran great, even while warmed up. I plugged it back in and it ran the same, until i came out a bit later to drive it, and right back to crap.

I should mention the car sat for a while, around 6monthes or so i believe. when i replaced the air filters, i hit the two together and they were so dirty and deteriorating it looked like i had hit two chalkboard erasers together, dust clouds everywhere. Because of the airfilters being so bad i thought maybe that was the problem, or the cause of the new problem. Iv replaced them of course but still have the problem.

Is it feasable that the dirt and dust from the filter being sucked through the intake could have gotten the MAF real dirty, causing it not to operate correctly? or affecting something else?

I have not ohm'ed the injectors yet, can anyone tell me what they should be at cold & warm?

I also have not checked fuel pressure yet, but i do know that it should be 42-44lbs.

I havent replaced the TPS, is there a way to check it to see if its the problem? will unplugging it do anything?

I thought maybe timing, but because sometimes it runs fine even while warm and sometimes it doesnt, im not too sure that would be it.

Im going tommarow to get cap/rotor, plugs, plug wires. Any plugs that are best for our cars? what about gap? (im also going to have the Ign. module tested tommarow)

Can anyone explain how to do the paper clip trick for reading the engine codes? The check engine light IS on.

Any other parts that may be the problem or other advice would GREATLY be appreciated! Thanks!

Rolling Thunder

Good afternoon, while I dont recall all the specific specs your looking for I do have a few suggestions.

First things first before throwing money at the problem I would check the codes. It just so happens that I made a short video on pulling codes because I get asked this question so many times. If you send me a PM with your email adress I will send it your way and it should explain everything. Once we know what the ECM is whining about that should help point us in the right direction befor you invest a lot of time and money.

Black88Z

Hey, i sent you a message.

I went and bought all the tune up parts, i will try to put them on tommarow.

I believe the injectors should be around 16-17lbs? and within .5 of each other is what i read.

What does it mean if the car runs and drives ok with the MAF disconnected, but misses, boggs down, and stalls with it connected? Would that mean the MAF is the problem? Or would it be "covering up" a different problem? (does the car run rich or lean with it disconnected? I believe its rich, but not positive)

Rolling Thunder

Yea that sounds about right for the injectors. The key is they should measure about the same so it will probably be quite obvious if they all read one value except for one which is half of the others.

Heres the deal with the MAF.... With the MAF disconnected the ECM basically says what the heck that signal can't be right ignore the MAF sensor output and run off guessed values programmed into the ECM instead. In theory if the MAF sensor was putting out bogus information causing the car to run crappy but not so crazy that a code is thrown then yes discconnecting the MAF and showing an improvemnt could be a sign the MAF is toast or at least in need of a good cleaning. Is that deffinetly the case no. Will it run rich or lean with it dissconnected? It could be either as the car really dosnt know how much air is flowing into the motor its just gussing values that are good enough to run the car.

Black88Z

Ok, i get it. The check engine light is on (as you know) so when i check the code(s) maybe that is it (or one of them). I will try giving it a real good cleaning, i sure hope this works because i have seen how much a new one costs!

Rolling Thunder

Agreed, a part like that is too expencive to replace unless its necessary. But anyways I sent you an email check it out and let us know what codes you find.

Black88Z

Thanks again for emailing me the video, it was very helpful. I did it and it gave me the folling codes:

1-2 (of course)

2-3

3-3 (High MAF signal)

3-6

4-3

I know what the 1-2 and 3-3 codes are, but the rest i dont know. Im not surprised that I got a code related to the MAF as im kinda thinking this, or is at least part of, the problem. If anyone can tell me what t he other codes are that would be great. I've searched this site for a list of all codes but didnt find one.

Thanks again

Tuned Performance

iTrader: (92)

23 is mat sensor low temp indicated, 36 is mass burn off circuit 43 is the esc circuit

Black88Z

Thanks, I actually was able to find an entire list on this site after all.

for 23... Does this just mean either the MAT or TPS sensor needs to be replaced? How can you check them? (My car runs fine when cold, would this help narrow it down? And it accelerates fine when cold, but when warm it boggs down real bad and will even stall.)

for 33 (High MAF signal)... Whats this mean?

for the 36.... What does burnoff at MAF mean?? also, how do you fix "missing pulses in ESC"?

And for the 43... What would cause low voltage to the ESC? What are the possible fixes for this?

Could the 36-43 be related? (ESC problems)


Also, for future reference for anyone else looking for the list of codes, heres the link: https://www.thirdgen.org/service-eng...ht-error-codes

Thanks for the help everyone, i really appreciate it. Alot of these codes are a bit confusing to me, im used to my carbed '81 trans am, things are a bit simpler on that lol.

Tuned Performance

iTrader: (92)

go to http://www.chevythunder.com there are codes and trouble shooting flow charts. you could very well have a bad ecm.

Black88Z

Ok, i will try this. Thanks

A bit of an update: I took off the TPS and cleaned and cleaned the part of the throttle that the TPS attaches to and when i put it back on, i re-adjusted it. I thought i would try adjusting it, maybe it wasnt adjusted right and that was what was causing it to run rich (or part of it.) My tach doesnt work so i had to play by ear and it took some trial and error but i adjusted it to where it sounds right. I think it might be just a little "advanced" but it seems pretty close. The main thing i want to point out here tho is this: it sounds like a completely different car now, and it never stalled or bogged down. It sounds incredible, it sounds like a nascars' car. It sounds so much more powerful than it did before, and it already sounded very intimidating. I noticed when i had my brother get on the throttle a bit heavy quickly and let off it puffed out some black smoke from the exhaust, but it has a cat-back on it, so that might be why. It doesnt puff out at all while idling or revved up "normally".

I did notice that it wamred up to a bit higher than ive ever seen it, im not sure if this is where it should be at full operating temp, or if it was overheating. i pasted a link below to a picture of where the temp was, but it was roughly 240 or so. it might have even gone higher but when i saw where it was i shut it off immediatly. My brother did notice it was leaking from the rad. cap.

Im a bit at a loss, prett confused. it ran with so much more power like this, never stalled or bogged down at all. The throttle was incredibly touchy, i'd describe it as "lightweight". It took nowhere near the throttle to create the same amount of power. It really runs and sounds great like this, but im not sure if it was overheating, and if so, why? My only guess is because i have the throttle set a little too advanced. (before it never fully warmed up, it stayed at around 160-180, occasionly hitting 200.)

Link:http://i656.photobucket.com/albums/u...Photo-0608.jpg

Thanks again to everyone thats helped, without you guys id be even more lost and confused than i am now.

Tuned Performance

iTrader: (92)

you might want to adjust the tps with a ohm meter .54v

Rolling Thunder

Ok ill start by explaining what these codes really mean

3-6 after the car has been run and is shut off the MAF sensor gous through a burn off cycle. Without getting into the physics of how the MAF sensor works inside theres a "hot wire" similar to a classic lighbulb element. Based on how much heat is dissapated from this hot wire as air flows by it the MAF sensor can measure the airflow. Problem is if crap gets built up on this hot wire it can throw off the readings. To compensate for this when the car is shut of it overloads the hot wire till it glows red hot and burns off and impurities. This code means that for whatever reason the ECM called for the burn off sequence to happen but didnt actually see it occure. This code could be related to your 33 code.

3-3 This means simply that the ECM is reporting a huge amount of air entering the motor beyond what makes sence for the given throttle position ect. Kinda like if i told you you motor consumed 6 billion cfms of air at idle it cant possably be right and a code is thrown.

43 This is your spark knock control. It means that the ECM detected a knock so it retarded the timing but still detected knocking. As a matter of fact no mater how far it retards the timing the motors still knocking. The ECM figures that cant be right if there really was a knock retarding the timing 20 degrees would have taken care of it if there was and throws a code.

2-3 This means that the temperature measurment is lower than expected. Because resistance of these sensors decreased with an increase in temperature if it was unpluged it would be equivalent to an infinent resistance and read by the ECM as extremely cold again colder that reasonable.

Unfortunetly you cant adjust the TPS by ear or by sound. All of the calibrations for the AF ration and timing ect are based in part off the TPS sensor. If you set it incorrectly the ECM will not even try to do the right thing because it may think your under part throttle when your just idleing ect. It may seem to run better because theres so many other issues causing the car to run poorly but that really needs to be set correctly.

Lastly the troubleshooting flow charts have been posted. There the same ones in the GM factory manual pretty much. Its very thoughough and will get to the bottom of the problem. Just pick a code and start chasing it down (after fixing the TPS though because some trouble codes are relative to the TPS).

Black88Z

ok, than you that makes alot more sense.

I will reset the TPS correctly.

Ill also do some of the troubleshooting today, ill post the results as i find them.

How do you reset the codes? Will just disconnecting the battery work? Maybe if I do that then a code(s) come back, it will be less codes? (i did unplug some sensors, and the P.O probably did too, so if its reset maybe it wont throw the same codes)

Rolling Thunder

Yes, dissconnecting the battery will reset the codes. May want to disconnect it for a minute or 2 sometimes the energy stored in things like capacitors can maintain the memory briefly (sort of like unpluging power adapters ever notice how sometimes the power LEDs stay lit for a short while?). Probably a wise idea as like you said sensors have been disconnected and codes are stored even if the problem is cleared.

Black88Z

Ok, i did this and the light did come back on. I have not ran the codes yet. However now i have a new problem thats got me pretty confused.

I adjusted the TPS correctly and started it and let it run for only about a min, then shut it off. It started fine and seemed to run ok for the short period it ran. I did not drive it. But then i did something else that should have been easy, that turned into a big headache.

I changed my cap, rotor and plug wires. I havent replaced plugs yet. But After changing the plug wires it wouldnt start. I figured it out, im so used to doing this on my 81 trans am that i did the plug wire order for on the distributor COUNTER-clockwise for pontiac out of habit. I fixed this and it started up, although it didnt run well. It smelled very rich and it was shaking the car a bit at idle (like one of the plugs wasnt firing), i figured one of the wires was possibly not connected to the plug well enough so i checked them all, they were all ok. I even made sure i heard them each "click" when they got on the tip of the plug. Still ran the same. I made sure they were all connected properly on the distributor - they are. I checked the firing order on the distributor to make sure it was in the right order, 18436572 - clockwise, (granted, this was last night and my only source of light was a not-so-bright lanturn and flashlight) but they all looked to be right. This is why im so confused. Another thing that throws me off is that i noticed the distributor base (where cap sits) has two holes next to each other for each screw on the cap (in other words theres two screws on opposite sides of the cap that screw into the distributor base, but where each screw mounts has TWO holes that it can screw into - total of two screws but 4 holes). I put the cap down and it sat fine on the distributor so i screwed it down like that, but maybe its supposed to be in the other holes??

The car will start but runs very poorly, and has NOOO POWER at all. It feels like the timing is off but i know its not. I verified TDC in cyl 1 and made sure the rotor pointed to cyl 1 and it did, i wired it up clockwise 18436572 from there. Its not backfiring through the exhaust or anything, but i did notice after shutting it off it had some smoke coming out the exhaust pipe, like unburned gas that was burning or something. Kinda grayish in color. I thought MAYBE if the cap is supposed to be screwed into the other set of holes that would cause it to run like this, it feels like the sparks timing has been retarded. The other set of holes would make the cap sit a few degrees more towrds the drivers seat, advancing the spark timing. Theres no knocking (that ive heard) but it runs very bad.

Im quite confused about this and thought i would consult others opinions on this before messing with it any more. Thanks for the help, its much appreciated!

ninetyone

iTrader: (2)

code 43 is usually your knock sensor

ninetyone

iTrader: (2)

i bet you have a bad knock sensor. You said "The car will start but runs very poorly, and has NOOO POWER at all. It feels like the timing is off but i know its not." In fact, look under cylinders 6 & 8. Should be a bell looking device on the side of the block. That is the knock sensor.

rgarcia63

"...but i did notice after shutting it off it had some smoke coming out the exhaust pipe, like unburned gas that was burning or something. Kinda grayish in color..."
It Is rich, beyond what the converter can handle. I can see the CTS causing this, but not the MAT.
The distributor ICM once installed will not move, the Distributor cap is notched to seal around the ICM so it wouldn't matter how many holes there are only one set will line up when the cap is properly installed.
"Missing pulses in ESC"; I would assume it's not receiving a signal from the knock sensor.
Sounds like fuel management needs to be corrected, and knock sensor circuit diagnosed, once that's done it should have normal power.

Black88Z

Thanks everyone for all the responses.

I will defenitly check the knock sensor, what your saying makes sense. Is there a way to check it?

However, before I changed the plug wires it ran GREAT. It had loads of power, i did multiple burnouts in it! Some were on accident too haha. I drove it to work a few times, around town, it ran great. Not 100% perfect, close to like 98% id say. but it sat for a while and i checked the plug wires-there was some corrosion in them so they did need to be replaced. Im not saying the knock sensor theory is wrong, but i dont see how changing out old, corroded plug wires to new and better ones would cause the knock sensor to act up, causing my new problem.

To me, because it ran- and ran pretty good- before the plug wires, cap and rotor were changed, to me it seems like the problem would be related to that. This is the first time i have done this on this car, so im thinking i probably just goofed up somewhere and didnt do something 100% right. Like i said, it feels like the timing is off or something, or maybe there is a cylinder not firing.

Im still very confused though, and id still appreciate more input on this situation.

Thanks again.

ninetyone

iTrader: (2)

I would also make sure that you didn't cross some wires somewhere. Like the two little harness plugs at the distributor module or the two plugs on the coil.

Black88Z

I went out this morning and looked everything over and found that cyl 3 and 5's plug wires were switched around on the distributor! So i switched them around and started it, it started up great! Like I said, this is the first time I i did this on this engine, annd i did it all at night, so im not that surprised that the 2 got mixed up. I let it idle for a few and watched it, the idle still surged a little, but not as bad as before. The idle was smoother too, and with the new plug wires and the TPS adjusted correctly the throttle response was as crisp as could be.

Im still going to look into the knock sensor, that sounds like a good place to start with trying to diagnose code 43.

Thanks again for all the help everyone!!