***update ** I started the car and it will NOT idle at all...it goes dead. If you give it gas it backfires or pops and then tries to stall. I held the RPM at 1100 for about 2 mins then cut it off...when I got out there was fire coming from the exhaust pipe and the CAT was BRIGHT RED. I ran and got the water hose and put the flames out. What now ???????

Background info:
I bought a 85 Vette and it ran perfect, drove it a couple thousand miles with NO issues. Lots of power, great gas mileage, lots of fun, etc.
Then the serpantine belt broke and the wife kept driving, result, blown head gasket and power steering pump went bad. I got a local shade tree mechanic to replace the head gasket and have the heads machined. He replaced the power steering pump, and put new plugs in. The car still runs rough but not like it did when the head gasket was bad. First off it would idle to low and stall, I unhooked the battery for a while then put it back on and drove for a few miles based on a tip from this forum about the computer learning idle speed. That seemed to help out some but it still jumps around.

The car runs fairly smooth as long as you keep the rpm's around 1100 - 1700 but it has a miss or sputters. if you go above 1900 rpms' it will cut out big time and the engine seems to want to flood. If you push the pedal to the floor it cuts out and bogs down and really tries to stall. The shadetree guy said a buddy came by and scanned it and said the "Cal Pak" was missing and that was causing the IAC to max out. Does anybody know what hes talking about? Why would it run great before?? But both shadetree guys said they didnt know much about computers, they usually build hot rod engines..

Next issue...at 1000 rpms and above there is a annoying scretch from what I believe is the belt or something its attached to. No noise below that level. If you turn the AC on it gets MUCH louder but again..only above 1000. Any Suggestions?

Another note. I read that the 85's had fuel pressure issues and that the gas tank needed to be around half full all the time. I took it and filled it up and put a bottle of injector cleaner in.

I drove the car about 40 miles yesterday and the temp never got above 189. But the computer said it was only getting 13 mpg...used to get 22 -26 before. There are no warning lights.

Another odd thing...not sure if its related or not...I noticed when I drove it around the block last nite, the dash lights would go very dim then really bright...Never did that before....

 

You could have multiple issues going on.

First I would check for vacuum leaks or lines left off. There is a lot of crap to put back and if he missed some lines it will do what you are describing. The dash lights are probably just your idle bouncing around so worry about the vacuum leaks first and go from there.

 

It could be caused by several problems. Have you tried unplugging the MAF and running the car? If it runs better then you could have a bad MAF. Also check the voltage on your TPS, it should read 0.54 volts at idle and steadily increase to 4.5 volts at WOT.

 

First off....it sounds like you have a serpentine belt issue, caused by the one of the pulleys it is driving, such as alternator, water pump, AC compressor, air pump, tensioner. Listen with a long srewdriver to each one. Don't overlook the belt being the problem, if it's old, replace it. Alot of what you decribed will go away when you fix that.

 

I unplugged the MAF and it will idol but if you give it any gas it stalls.

The serpentine belt is brand new and I got the best one Oriellys had.

 

I am certainly NOT as good at troubleshooting as most of the guys on this forum. But I would like to offer a couple suggestions. If someone reading this feels I'm in error, that's OK, I'm open to correction. Like one of the guys said, it sounds like Mr.Shadetree may have crossed connections, or left some off all together, allowing some serious leakage. Also, for those of us with a mass air flow sensor (85-89?), I don't think we have a "Calpack" in our ECM, but rather a PROM chip only. I think Calpacks are used with a prom in speed-density setups.

Also, it seems to me that your idle problem could be as simple as the wrong gasket behind the throttle body. Make sure it has the obvious holes for the throttle blades, and also the triangular hole for the idle air control to allow air thru, as needed in TPI's '85-'88. I've heard of the wrong gasket, ie no IAC hole, causing all kinds of idle related headaches as the throttle blades must then allow the necessary air in, but the ECM tries to keep them shut to let the IAC do its' job.

As for the superheated catalytic converter, it makes me think that there's WAAAY too much gas getting thru. (Also you mentioned you're only getting 13mpg.) So much that it can cause the red glow and fire in the tailpipe. Pull your plugs to see if the flooding is only in certain cylinders or in all of them. If it's only certain ones, some injectors may be installed poorly causing them to be jammed open or they may be jammed shut causing the others to overcompensate by being wide open.
If it's all of them, then the flooding is being caused by a more centralized problem. Could the pressure regulator be set/installed wrong?

Finally, if any of the forum members live near you, is it possible for the two of you to get together for a side-by-side look to see if everything is properly connected? I sure hope this helps. I've been in your shoes before on other cars

One other thought, and I hope the other guys will consider this, I don't know how many miles are on your car, but what are the possibilities the timing chain has jumped a tooth and now the computer can't get it's timing right no matter what it does? If the timing is severely retarded,(no jokes about me please) then wouldn't the engine have trouble gaining speed? Meanwhile the sensors are all telling the computer to give the injectors every thing it's got, causing the fuel dump to collect in the cat. convertor leading to the bright red convertor and fire in the pipes. OR possibly MR.Shadetree put the distributor in a tooth off,(or wired it incorrectly)and was initially able to time it out, but now who knows what is happening.

 

Just for the heck of it, I would check the spark plug wires to make sure the firing order is correct.

 

The only time I have seen an exhaust system "glow" is when someone had forgot to tighten down the distributor clamp and the distributor was turning itself (advanced?). I would check the timing right away.

 

YUP! Timing is crossed, or way off.

My $$$ is on that for starters...

 

I had a small break in the rain today so here is what I did.

I started the car just to see if it would idle...it would not. I shut it down and then pulled all the plugs one by one.

Plug 2 and 4 were dry but had some black on them.
All the rest were wet with gas and also had some black on them.
These plugs are brand new and have less than 50 miles on them.
I dont know if this points to anything but it just seemed odd to me.

One more thing...this will probably be a stupid question but oh well....I am going thru my Haynes Repair Manual and reading how to adjust the timing. Where is the "distributor hold-down clamp bolt" ??

 

The distributor clamp bolt is at the base of the distributor, on the intake manifold, back of the engine.

I'm bettin' the shadetree hack crossed some wires, among other things. Check that first. Make sure they're at least sequenced right, by firing order. You can find a schematic in haynes of the distributor and cylinder #'s.

He probably didn't seat the components well either, and you have vacuum leaks.

Get as much cash back from him as you can.

 

Thanks for the help with locating the bolt. I will try that tomorrow.
I did run down all the plug wires and they are in the right order.

Freakin get what you pay for I guess. This guy came highly recommended. He builds lots of race engines. The manager at Oriellys has two engines built by him that he races and i was impressed when I saw pics of them. Guess that dont mean jack when it comes to working on a C4...

 

Check for stored codes in ECM, check for fuel in fuel reg vacuum hose, and check your fuel pressure and bleed off time.

 

You're sure - like you'd put your life on it?

You can't scratch stuff off the list till then...

After double checkin' the wires, check fuel pressure like 86 said. I don't think that's the problem, but you have to check to take it off the list.

Check it when it primes the rails, and post back.

 

right on the money i bet

 

I am not that sure about anything...
I do not have a plug wire retainer ring and the plug wires are not original so it makes it a tiny bit more difficult.
Can someone point me to a pic of the distributor and the right numbering?

Problem with checking some things is the car will not idle at all and will barely run if you sit and baby the gas. It sure is not steady in anyway.

 

http://members.shaw.ca/agent86/Spark...g%20Wiring.pdf

 

Find cylinder #1 - driver's side front. Follow the wire to the distributor.

Right now, don't worry about where on the distributor it is.

The next wire clockwise, looking down on the distributor, should go to cylinder #8 - passenger side back. Keep your finger on the distributor to not lose your place.

Check carefully. This is only for sequencing, not timing.

ed.: Beat me to the punch 86...

 

Starting w/ the firing order; 1-8-4-3-6-5-7-2. here's a pic of mine. When I changed over my intake, I labeled everything. This isn't a complete photo of the dist., but it should get you started. Best of luck, I hope this helps. BTW, when you go to check the timing, be sure to disconnect the ESC wire. It's a connector with a TAN wire w/ BLACK stripe. On my '88 it's near my brake booster. I've heard that on some years it's in different locations, but always the same color and easily found. This MUST be disconnected to check/set the timing. If you don't, you can mess with it all day and it'll still be wrong as you'll be fighting the ESC.

 

Awesome...thanks for all the info !
As soon as it stops raining I will get out there and go over the wires again to DOUBLE Check...

Is there a diagram of the vacum hoses and where they all go ?