'86 305 TPI with only 73K on it. The car has had a drivability issue for a couple years that I never really could track down, and because of that it has seen VERY little use. This last spring I got rid of the EGR and the car was plenty drivable, didn't run perfect, but it was bearable. Drove it a couple times and then decided to wash it. After washing it, I went to pull it into the garage, suddenly the car did not want to run without keeping your foot on the gas and holding the RPM's up over 1500. There was also a fair amount of black smoke.

I said screw it and double peddled it into the garage where it sat for a month because I was mad at it. One day I tried to run it again, and it was still having the problem. Got mad at the car again and it has sat till now. I can't figure out what's wrong with it. Everything checks out OK. Fuel pressure is good, the regulator works fine and does not leak. Cap and rotor look good, plugs and wires only have about 13K on them. Could it be a weak coil?

Also, I have always suspected a minor head gasket problem. The car has always built up pressure in the cooling system a little faster than what I consider to be normal. Tonight it was about 40* when I started the car a few times. Total run time was no more than a minute tops. There was enough pressure in the system to make the upper hose start to get firm. I loosened the cap and it girgled into the overflow bottle a bit. I KNOW that ain't right, but could it be causing the other problem? I want to get all the running issues taken care of before I drop in a 350.

 

Black smoke is running rich. How did you disable EGR? The valve being stuck slightly open would case just the issues you are seeing. (of course, there are only about a dozen other things that could cause it as well....) Any codes set?

 

I forgot that this had also happened a couple times last year, but the problem just vanished for a while. As long as I have had the car, it would occasionally set a code for the EGR, so this year I deleted the EGR and solenoid. The valve was replaced with a block-off plate, vacuum tubing was removed and/or plugged. It ran pretty well for about 100 miles, I thought I finally had it licked. Then the problems suddenly started again.

 

Did you reprogram the prom to ignore EGR?

 

I was about to have that done, but then the issue started again. It would only cause the light to occasionally come on, which is the only reason I was going to have it edited out of the programing.

 

Get it edited out of the prom. An egr code can cause the computer to do odd things with timing... or simply just run on preset tables, with no consideration of sensor input to tune the mixture... makes the car run rather odd. Get the EGR codes cleared out, and edited out of the prom, and see if that doesnt make the problem go away.

 

I have deleted the EGR on others before, there are no obvious effects, other than the light coming on at times.

Also, I have experienced what it is like when and EGR sticks open, and this car doesn't act like that. A stuck EGR will usually cause the motor to spit and sputter, then maybe die. In this case, as soon as you take your foot off the gas, the motor just quits. If you keep the revs up, it seems to run fine other than the smoke. It's weird. It's like if you lift off the gas, it shuts off the ignition.

 

unplug the maf sensor and see if it runs better, if it does replace the maf sensor relays.

 

I have tried that too, still the same.

 

Do you have a scanner? If so, check and see what temp the computer thinks the engine is when the problem presents itself.

Have you checked all of your grounds? That would lend some rather funny sensor readings...... and make the engine to odd things.

Ohm checked your injectors?

Does the problem come up immediately, or does it run ok till it warms up? Does it set any codes other than the EGR?

 

I have a scanner at work, maybe I can bring it home one night.

I have not checked any grounds. Will do.

I checked the injectors last year, they were fine then. I will check them again though.

The problem starts immediately, you have to get your foot on the gas lightly for it to start and run. There are no codes, it has to be driven to set an EGR code (when it was running better). Before it was deleted, however, it would set an EGR code on a cold start.

 

Check the TPS for correct adjustment. Also, I would be interested to see what your coolant temp sensor has to say....... (there are two, one for the gauge, one for the computer, the one for the computer is what I am interested in, need a scanner for that....)

 

I can tell you this much. I have the service manual from pontiac for my 86 TA and i have the 305 with tpi. The EGR is a pretty important piece of equipment. The problem is that gm doesn't make them anymore... nobody makes them aftermarket either. Are you getting a SES light? If you are get the gm code reader. if it is a code 33 then what could be causing you run problems is your mass air flow system. As for your fluid problem i don't quite know what that would be. You can run some simple tests with a 12V tester or a voltmeter to find out if it is infact the MAF system. So check the MAF burn-off relay, the MAF relay, the grounds within the MAF, and the sensor. a vacum leak will do it too.

 

1)Have you looked or considered the MAF sensor itself?
2)High coolant pressure-bad rad cap!
3)Cold start injector(The 9th injector)....Do you have one?......and could that be a problem to?(ANYONE)?
4)Timing- have you checked that out?......should be 6*

Just a couple of ideas!....Sorry, thats all I got for now!

 

A gunked up cat could account for a lot of these problems, but as others said, could be a buncha stuff.

 

The EGR and solenoid had been replaced years ago trying to fix a cold start issue. It never went away, untill I deleted the EGR. All the MAF stuff has also been replaced previously. I'll check them again though.

The problem with the cooling system pressure is that it builds up faster than it should. Probably a blown head gasket or a cracked head, I assume.
Timing is good. The cold start injector operates, but that's all I know.

I don't think the cat is clogged, the exhaust actually sounds a little louder than it used to.

I also adjusted the TPS last year. I also am very curious as to what the coolant temp is reading at. I'm waiting until I bring the scanner home to check everything out.

 

Well is there any way to test the IAC? I am wondering if it wouldn't be the IAC. The IAC is supposed to send a signal to the ECM and then compensate for a loss or rpms or bad mixtures and compensate. if the IAC is bad then it wouldn't compensate and sputter out and die. So do you guys know how to test the IAC?

 

When properly adjusted (which I think it is), the idle stop screw will allow the engine to keep running even when IAC is completely closed.
If you get on the gas, the motor seems to run fine in the upper RPM's, but there is the blackish smoke the whole time.

 

I will put up what the service manual says to do and the trouble shooting chart. I just found out that two of the terminals on my IAC harness are not giving me 12 volts like they should. i am wondering if maybe you have the same problem...

 

Here are the scans of the service manual. ummm this is a problem... how do i post up pictures to this forum? they are on my hardrive not through the internet? if some one can give me a solution to that i can post those pages.

 

and oh noes!!!! based off the tests in the service manual!!!! the ecm is bad. make sure your ecms are ok. 12 volt tester will tell you if it is ok or not.

 

I think you have to have the pics on photobucket or similar to be able to post them.

I brought the scanner home, but I forgot the cord I went ahead and started playing with the car anyway. I started it up, kept it going and occasionally revved it a little. After running for a minute or two, there was no check engine light. By that point, I could get the RPM down to 700 before it started to stall out. If I let off the gas, it would die immediately.

So then i turned up the idle screw until it would start and run on it's own. I did not hear any vacuum leaks and there did not seem to be any black smoke anymore. I started spraying carb cleaner in different areas to look for a vacuum leak. There did not seem to be any change in RPM anywhere.

Although, the RPM did slowly rise when I sprayed around the EGR block-off plate. However, the RPM never came back down, so I think it was just a coincidence. After that, I adjusted the idle screw back down to get the idle at 1000 RPM. Seemed to be running pretty well, and throttle response was good.

At this point I'm thinking either the IAC valve or the coolant temp sensor, or both. Now that the motor should be cool again, I'll go ohm the injectors and see what happens when I try to start the car again.

 

Did you check to see if the bolts on the EGR block off plate was tight? Could the Block off gasket be leaking??? "Although, the RPM did slowly rise when I sprayed around the EGR block-off plate."

 

I specifically remember tightening them down, so I know they are good. The RPM went up, but it stayed that way and never came back down (on it's own), which makes me think it was just a coincidence.

 

The injectors still ohm fine. It started up and ran on it's own, but it was idling a little low. When I disconnected the timing connector to check the timing, it was very hard to keep it running. Timing was good at 8*btdc. Reconnected the timing wire, and the timing advanced like normal. After a couple minutes of running, it was idling higher and smoother. I don't think the IAC is operating.

 

Ok i got the stuff up. go through it and do the trouble shoot. instead of testing the circut like they tell you to when you get at the lower end past the 12v tester on the pins on the IAC just check to see if your getting power at your ECM. check the leads at the ECM.
http://s840.photobucket.com/albums/z...t=scan0002.jpg
http://s840.photobucket.com/albums/z...t=scan0003.jpg
http://s840.photobucket.com/albums/z...t=scan0001.jpg

 

let me know if that helps you out and solves your problem.

 

Im going to go ahead and agree with the statement that the IAC is probably NOT operating, It would seem to me as if you have an ECM problem, let us know what happens

 

it is in fact the ecm. I will get a hold of the replacement ecm in the next 2 days. I am extremely suprised. the ecms are cheaper than the mass air flow system. How is it that the brain of the car is more expensive than that one sensor? 80$ will get you a new ecm from you local shucks oreilly auto parts for all of those who might need to look for an ecm. they are remanufactured parts just incase your wondering.

 

Try this MAF Sensor test.

https://www.thirdgen.org/forums/tpi/...uble-code.html

Also if the ECM is bad, its actually not that expensive. Its only $100 for the BWD ECM and $80 for the Cardone (remanufactured). Check it out
http://shop.oreillyauto.com/ProductL...pe=248&PTSet=A

 

I had my own problem back in Sept. I priced out a New MAF Sensor from GM....$1979.00(new).....$300-$500(reman)!!!! HOLY CRAP! It has been fixed since then, turned out to be the relays.....$15.00

 

Yup. Thats the same price here where Im from. I asked the GM Parts department if they do price match. They said . The GM Sales Department Rep. actually told me to go to Autozone and buy there. I got cocky and asked whats the difference. He said nothing. That they all have the same chip values, chip boards, and quality. They major difference is whether it is a remanufacture (rebuilt) or plain spanking new.

 

According to this test, I have a bad IAC valve. But, I do not fully understand this test. You are supposed to get the car up to temp, notice RPM. Then shut the car off, disconnect IAC, start, note RPM. It asks if there is an increase in RPM, there is not. But... How could there be an increase if the the IAC had just been unplugged? Does it open up when the ignition is turned off? That's the only reason I can think of.

At any rate, I have power at all four connector pins, so I will replace just the IAC valve. I also will replace the CTS while I have the alternator moved out of the way. Hopefully it will start and run well every time after that.
Then the 350 and T5 can go in

 

When you replace them both, let us know what happens. Im curious.

 

Good news everybody! the idle is fixed! check the connector on your MAF sensors. the problem seems to be that the wires on the harness get beat up being next to that alternator fan on the vin f fuel injection TPI rigs. The belt will rub through the wire and coating. that fixed my code 33 and now i just have to finish off my egr to get rid of my code 44. but that is an easy fix. she is drivin really well now. she will idle at 500 rpms easy and the surge is gone! check your MAF system.

 

There should be, or was a clip for your MAF wires that clips onto the upper rad support to keep the wires away from your cooling fans, alt and belts. Look for it or go buy one, mine is black plastic.

 

I'm fairly certain that my car finally runs how it is supposed to. I changed the IAC and the CTS, set the idle screw back to where it was originally. The engine was dead cold and it started right up without hitting the gas pedal. Every start, the RPM is up close to 2K, then settles down to a normal idle. Throttle response is great, and it does not die when put into gear.

For as long as I have had this car, I don't remember the RPM ever being higher after starting the car. It always seemed to be about the same or a little higher than idle. When I removed the old IAC, the pintle was extended out all the way. I'm guessing that it just decided to get stuck there that day earlier this year.

If it is dry outside this weekend, I'll take the car for a drive or two and see how it runs.

 

Took the car for a drive. It ran fantastic... for about 4 minutes There was a sudden lack of power, then the engine light came on and the throttle response was bad. Turned the car off for a couple minutes. Started up and ran fine... for about three minutes, then the same thing. Every restart after that, the light came on sooner and sooner.

Now I have a code 33. This is getting to be VERY frustrating. The relays and MAF have all been replaced previously, not many miles on them. If I unplug the MAF, and then drive the car, it does not really improve, it just changes the symptoms a little bit. Does this sound like a bad ECM? The code never sets just parked and idling. It will drive just fine, then suddenly it screws up, out of the blue.

 

ecm does sound like something I would try, though do you have one to test with?

 

I could borrow one from one of my other cars, but I don't think I have another prom to try if that is part of the problem.

Now that I think about it, this current problem is very similar to one I was having with my other '86. It just didn't have the problem nearly as often. That car is not stock anymore and has a custom prom with the code 33 completely turned off, which took care of it.

I suppose an ecm and prom from my '88 350 car should work for testing.