Starting a new thread because I can't seem to get anyone to respond to my original. Please see my post 87 Yellow Iroc No Start for all the details to this point.

https://www.thirdgen.org/forums/tech...c-project.html

After getting it all back together, it sounded a heck of alot better. It was finally hitting on all 8 cylinders and sounded strong revving up the motor, but it just would not idle. Was getting one code 32 - EGR. Soooooo, today I spent most of the day digging my way back to the EGR valve. Checked it with a hand vacuum pump, held vacuum fine. Took off the EGR and made sure the intake passages were clear, cleaned it all up and put it back in. Also put a new coil on today because it was the one thing I had not done as of yet.

Done ohm test on my new southbay injectors again just to be sure while I had them out.

Started the car and great! No more code 32. Now getting code 33 and 34 and it sounds worse than ever. I'm at my wits end here. Can somebody please take me by the hand and lead me down a road to recovery? I love working on things and fixing them myself. I get alot of satisfaction from it, but this is beginning to be very, very frustrating.

Thank you ahead of time for taking the time to respond!

 

If your pressure is that high, you need to fix that A.S.A.P. The person who told you 60psi for your fuel pressure is either a idiot or trying to cause serious issues with your car. My 1988 383 TPI IROC is highly modified with a adjustable fuel regulator that I have set at 43psi. If I start raising it higher than say 46psi I start to get unburned fuel in the exhaust. In other words your pressure is way to high, maybe even dangerous!. Also did you get the exhaust fixed? It will help by giving you back pressure, that should help a little in holding idle. Another thing to look at too, is your TPS AND IAC. Theres a link I attached for setting and adjusting.
https://www.thirdgen.org/tpimod2

 

60 psi is way too high. If you have some mods, like headers, larger runners, ported MAF, bigger coil, better filter, ported plennum, 3" cat back and you are still using the stock chip, them you can turn up the fuel pressure up to about 47 to 50 psi. That's what TPI specialty recomended in the past to make up for the extra air coming in to the engine. Higher pressure will cause problems.

 

do the tps and iac procedures above.
re check your timing <-
if no go pull a plug and check its condition, if its covered in black soot, its running too rich. get back to me with results.

 

btw, clear the codes by disconnecting your neg batt cable for a minuet. also you can set certain codes by disconnecting harness with the key on or car running, so if you unplugged anything your getting a code on, clear it

 

Same here. I probably need to drop it a couple of psi.

 

Ok, thank you to everyone for finally getting with me on this. From the beginning the fuel pressure was right around 43psi. I've not changed anything there other than put in a new fuel filter. Have not checked the pressure again since all the motor work. I read lots of posts on fuel pressure and felt the 43psi was correct and ok. My TPS is set correctly at about .55 and moves smoothly to WOT to +4.00. I have not done anything with the IAC because I felt like if it won't idle worth a s*** that all that done was set my idle correctly once I had it running good. Am I wrong there? Besides right now, the only way to keep it running while I mess with stuff is someone in the car feathering the throttle. Like I said before When I got the newly reconditioned stock 305 heads back on and everything back together and started it, it sounded alot smoother, hitting on all cylinders. Sounded good revving up the motor. At that time I could unplug the MAF and it would idle but sounded very rough and missing occasionally. Maybe I should have tried setting the IAC then. Well after taking off the EGR and cleaning and checking it yesterday and putting it all back together, it sounds worse than before. Everything is stock on this car except I'm told that it had/has a mild upgraded cam. I know nothing about that.

 

I have all new exhaust to finish installing. I have the y-pipe and the cat on and that is it to this point. Need to get it on a lift to get it high enough to snake my long exhaust pipe up over the axle and finish installing the muffler and tailpipes. It just has stock exhaust manifolds. No smog pump and the little funky pipe looking things that were attached to the exhaust manifolds have been removed and the holes have been plugged.

 

Is the torx head screw that you set the IAC on the right side of the throttle body as you look at the engine from the front? Its the screw that sets the stop for the throttle linkage correct? If so, the silver plug is still there so I guess it's never been touched since the factory. Should I still try and set this with the missing problems I'm having now and will that mess up my TPS setting so I will have to do it again also? And with the codes 33 and 34 I am now getting, is my MAF bad? I have cleaned that once with MAF cleaner and before the EGR deal the car ran best with the MAF unplugged. Now it doesn't seem to make a difference.

 

One other question. After getting my heads back on and searching all over the this site, youtube, my Chiltons manual I adjusted my valves per the manual basically. If the valves were set too tight or loose would that cause it to run poorly? Like I said before it really sounded good other than the idle issue for the most part when I first got it back together. Could the valve adjustments have changed much since then with all my running of the motor. Should I go through them all again? I adjusted them originally per the manual with the engine NOT running. Figured once I got all the exhaust on I might check the valve adjustments while the car is running.

 

Also wanted to mention, I completely rechecked my timing for the 10th time on this last night. Turned the motor by hand with thumb over spark plug hole, took dist cap back off and verified rotor placement, the whole nine yards. Even unplugged all my new plug wires and traced them again to make sure they are hooked up in the correct firing order. I just don't feel like it's a timing issue. O and yes I had the EST unplugged setting it.

 

Oh, one other thing I thought of if it matters, is to start the car I HAVE to hold some throttle to get it to start. Other wise it just spits and sputters and will not come to life. I prob will check my fuel pressure again this afternoon, just to be sure.

 

well you were asking if the valves wre to tight would it cause a problem... yes.. because it wont allow the vavles to close all the way to build compression.... and have you dont a cranking compresion test on this engine? i looked at your last post but i didnt see and psi readings?.. and if you have compression problems get a kit to put shop air into the cylinder.. so u can see where its leaking off....

 

To address the code 34 and 35. You've got a vacuum leak somewhere. I've got the same car you do except it's a 350. Check the condition of all vacuum lines and make sure they are all accounted for. This will cause these codes as well as rough idle. I'm not saying this is the only issue you've got going on but it is a good place to start. Get you a vacuum gauge from auto supply if you don't have one. Autozone and Advance carry them relatively cheap. Good luck.

Steve

 

Do you know of anyone else that has a tpi with a MAF you could borrow and see if thats the problem? Also try checking the boneyards around your area and see if they have a TPI MAF. Parts are usually pretty cheap at the boneyards.

 

I agree with the last post, although I thought he said he already did that.

 

I have not checked any compressions since the head replacement but know it does have compression on all cylinders now as I could hear it on each cylinder as I turned the motor by hand adjusting valves and doing my initial timing set. I just took the vacuum gauge back yesterday. I do still have a vaccuum gauge. Before doing the whole EGR thing, anywhere I put the vacuum gauge I would get between 5-10" of vacuum at idle. Felt like it was good. But there are some old vacuum lines still on the car. I have unhooked any I was doubtful of and blew through them just to make sure they were clear. Should I still replace them?

 

Another thing just want to bring up. You know there is a temperature sensor on each head just under the exhaust manifold. If I understand correctly the one on the drivers side is supposed to be the one for your dash engine temperature gauge? If so, when the wire is plugged onto it, it does not work. The previous owner has a temperature sensor and guage pluggen into the lower part of the block on the drivers side. The gauge is just laying inside the engine bay. It does register the blocks temperature. I figured they done this because they could not get the dash gauge to work. Also the one on the passenger side, the connector to the sensor is kind of messed up and I'm not sure it's even getting connection well. Do these two sensors have any ramifications to the ECM and my problem?

 

Ok. I guess I missed the post about checking vacuum. However, if you are getting 5-10" of vacuum at idle, that's low. You should be getting a minimum of 15". Understand, I'm only basing this on my issues. Once I got the vacuum above 15, Several problems went away. I'm not an expert by any means. Just my 1.5 cents.

 

Ok, I'm going to look into this vacuum thing more. I've been still thinking that is part of my issue. Where were you checking your vacuum at?

 

I usually check it at the T that goes to the vacuum canister. Looking at the car, in the front right in the vicinity of the charcoal canister. Based on my past vacuum problems, I wouldn't recommend unplugging vacuum lines just because it doesn't seem to be doing anything. On these cars, vacuum affects things that you wouldn't suspect. For example, my vacuum was dropping to about 14.5 at idle. Couldn't find a leak anywhere. Turns out the pcv valve wasn't seated correctly. Got it seated and the vacuum rose to 15.5. This is about the best I can get. My engine has a high energy cam among other things that will drop vacuum. If you can get it back to 15, I think you'll see a big difference.

 

Ok, thank you. I just was not sure what amount of vacuum I really should be shooting for.

 

Minimum compression for combustion is 80psi, I don't think I can hear the difference between 60 and 80psi.

 

rgarcia63, your right. After messing with this today some more, I'm going to recheck my valve adjustments and check all the compressions again. I rechecked my fuel pressure again this afternoon. 43 psi right on the nose. Something is up with it not firing on all cylinders again. It sounds like it's just hitting on about 5 or 6. Rich smelling also. I will go to the basics first though. Compression.

 

Before I forget.
Early on you posted a TPS voltage range of .55 to 4.00 vdc.
The ECM supplies a 5.00 vdc reference to the TPS and a couple of other sensors.
The reference voltage shouldn't drop below 4.5 vdc if it does disconnect each sensor that uses the 5vdc reference until it rises backup to spec (that sensor is pulling more voltage than it should.) If it doesn't rise above 4.5 vdc with all the sensors disconnected then the ECM 5vdc regulator is faulty assuming no wiring problems. Unfortunately that fix requires replacing the ECM.

 

Ok update on where I'm at. I want to thank everyone for all your great help. It really wasn't until rgarcia63 spoke of the compression that I figured this out. Hopefully someone else can learn from this. I just couldn't see how my compression could now be low after just reconditioning the heads and putting everything back per the manual until i really got to thinking how I had adjusted the valves. I had them misadjusted too tight. If you are adjusting valves on a 305/350 chevy motor for the first time after a rebuild or something of this sort, make absolutely sure you do not overtighten them as it will not allow the valves to completely close. Watch this video:
http://www.youtube.com/watch?v=89o5rLpbCgI

This video will tell you to just add 1/2 turn beyond no valve lash. I read 2 other sources that one told me a full turn and another 1 1/2 turns after no lash. So I did 1 full turn. Then......turned the motor over a few more times and noticed certain ones appeared loose again and tightened them some more. This is a definite no - no. You can always go in after you get it running and tighten them more to take out the clatter if there is any.
Yesterday after I completely went through them all and followed the video I mentioned above, problem solved. Sounds great and all my vacuum problems solved. 14-15" of vacuum now. I read all the time about people throwing parts at motors instead of finding the root cause to your problem, which will generally save you money in the long run.

I have no more codes currently either. Now I'm on to some other small problems. Neither one of my electric fans will kick on. Also temperature gauge in the dash is not working. Can you help me out with these issues?

Thanks everyone.

 

I need to replace my fan switch and wiring harness connector to this switch. Summit Racing have ones that will turn the fans on at a lower temperature. Does anyone see any problems with the fans kicking on at say 185 degrees instead of the 220-230 factory specs? Also where is the fan relay at?

 

If you have 2 fans, one is for the radiator cooling and the other is for the AC. I have a Hyper-tech cooling fan switch. Which is setup on the passenger side cylinder head. I have not any problems with it. But you will need to change your thermostat to a 180º. Also I can't remember for sure if the ECM will compensate for that or not, as I have a custom chip for my ECM. As far as were the relay is located, mine is behind the passenger headlight. I'm not sure if that's a stock location though. Try and get some wiring diagrams, and identify the wire colors for the relay. Then chase them down in your car to make sure you have the right one. You can also test the fans out once you locate the wiring for them by grounding out the one of the 2 wires which will turn the fan on. Thats how the switch works by grounding out the wire for the fan when it reaches a certain temp.

 

Ok, thank you, will work on that. Do you have any input on the dash engine temperature gauge? Am I right that it is run off the temp switch/sensor on the drivers side head under the exhaust manifold? How can I test it? I know the gauge in the dash is just a plug in gauge so could the gauge be bad or suspect the sensor or wiring?

 

I have a aftermarket water temp. gage in a gage pillar which reads of the temp. senser on the passengers side. I was told years ago that doing the modifications to engine, I should get a more accurate gage. Plus stuff does wear with use and age. I don't remember off hand what side the factory gage reads. I'm sure someone else on here would know, or again get some wiring diagrams. If your serious in restoring the car and are willing spend a couple hundred bucks. Get a Helms manual, you can find them on line. You can pretty much build the car from the ground up.

 

Yeh, I'm always reading on here that alot have the Helms manual. I will prob get one. I have a Chiltons. Thanks for all your help and input Americanmouse and the rest.