HughG

After wasting a lot of time and money I decided to take my car to a mechanic that supposedly knows all there is about crossfires. The first thing he seen was that the fuel pressure was only at 6psi, so he changed the fuel pump and got it up to 13 psi... but this didn't fix the problem. He has now been running test after test on it but has not come up with a solution. He claims that the problem has been here for some time and instead of identifying the problem everyone just kept throwing parts at it hoping that the problem would go away... it didn't. This mechanic, who was confident he was going to fix it, told me today that "I wish I had never seen this car." I find it hard to believe that a car from 1984 could baffle everyone so much. He claims the spark is low and he is surprised it runs at all, it all comes down to bad wiring, a wrong distributor or a bad computer... he says that so many new parts are on the car that it is hard to tell if something wrong may have been installed that doesn't work with it. If anyone out there has any suggestions on what may cause a low spark and the car to load up with gas when you first start it, please toss your ideas this way. I have a bad feeling that I am going to spend a lot of money with this mechanic only to get the car back and find it is still not running correctly.

ben73

Don't forget about the temp sensor in the front of the intake. The early 84's have a older style connector on this temp sensor that is troublesome.
New sensors often come with a new connector and pigtail to splice in place of the old connector.

These older type connectors look similar the the connector on the knock sensor, and the later replacements are a 2 terminal weatherpak type with the 2 terminals side by side...

The older type often short circuit in the connector and tell the ECM that the coolant is something like -40F and it responds by increasing the fuel delivered.

I can dig up some pics if my description is lacking.

Tom400CFI

I agree, and think that this should have been one of the FIRST suggestions, for the symptom of "dumping in too much fuel".

Also, are you sure that the o-Rings that seal the injectors into their "pods" are sealing? Do you get fuel leakage with key on/engine off (like when the fuel pump primes)?

This system IS very simple and shouldn't baffle anyone that calls themselves a mechanic.

-Tom

jhammons01

^^The part about the Mech being baffled is a Red Flag to me.

The FSM usually is dead on accurate for trouble shooting electrical issues. Whenever I followed the prescribed trouble shooting guides from the FSM....it led to a faulty component (which solved the problem) or faulty corroded wiring leading to that component (which also solved the problem)

ben73

This is especially true. The Crossfire is essentially the same as the TBI setup on MILLIONS of trucks built thru the 80's and 90's except the 2bbl TBI unit has been chopped in half and had a 8" long linkage installed between the 2 parts!

HughG

The person before me replaced the temp sensor, I could see it was replaced since it was the newer two wire unit (and it looked brand new). The guy I bought it from made me believe that it was the injectors, so I blew over $250 on two brand new injectors and it improved the spray (it was dumping out before) but still did not fix the problem. I was tired of just guessing so I took it to this supposed expert on crossfires, I was told he was a trouble shooter for crossfires when they first came out. At this point, after doing extensive testing on everything he has come down to either the distributor or the computer since the timing is all over the place. He says that the distributor has been replaced and the numbers on it do not match the numbers of the only two distributors that will work with this setup. So, I am currently waiting to hear the results (the part was due in this afternoon).

I would have continued to work on this myself but I actually need the car for a daily driver and I was embarrassed on the way the car sounded when you first started it (popping and bogging down). Plus, if it was getting too much gas I feared that the oil would thin down and I would start washing out the rings and run into so bigger problems.

If this guy doesn't get it done this week I will probably have to get it and start all over. I can't see how it could be this big of a problem... very frustrating. The guy working on it just spends a little time on it each day in between other cars, so I hope that it gets done soon. If no one can figure it out I will have to resort to bypassing the computer and putting a carb on it, which I really don't want to do.

I hope I will find out the problem this week and can post it hear in case anyone else runs into this kind of frustration. Hopefully no one does.

Tom400CFI

Let us know if you get it back from teh mechanic, still not working correctly. We'll walk you through it, and get it fixed.

T. Wayne Nelson

Tom, you don't think he took it to TAS Auto the Corvette specialists do you...

mrmmoore

Hugh,

Try checking the EGR control Solenoid and see what happens.
(mine was dead)



To see if it changed anything, I unplugged the electrical connector, unplugged the vacuum line to the throttle body then plugged the port on the throttle body.

Good Luck.

Mark

Tom400CFI

None of what the OP described for symptoms, points to the EGR malfunctioning. His symptoms are way more indicative of a bad CTS or leaking injectors/o-rings.

rad928music

Id Check the coil.
Sounds like the problem i had with my TBI 2.8 Blazer.

If you havent already id post in the C3 section since some the late C3 where Crossfire.

Also try posting in the TECH Section May get more views.
good luck

Tom400CFI

This is also not symptomatic of a coil. Stop GUESSING people. You're going to confuse and cause the OP to replace parts that don't need replacing.

There are plenty of people w/solid CFI experience on this forum. I owned one for 12 years. When I sold it, it was ~130 hp stornger than stock, ran low 13's and returned 24 highway mpg...on a stock-like idle.

HughG

One of the problems with this car is that all of the smog controls have been plugged off. Also, the EGR has already been disconnected. Still no word from the mechanic... I have worked on a lot of cars and have replaced engines and do all repairs myself, I just felt I was getting no where with this and everything I tried seemed to make it run worse, not better. I thought I would quit guessing and give it to someone with the equipment to do proper testing. I had already dumped $300 in parts that did me no good, figured it was better to pay someone that knew what they were doing. Although with the car having been there almost a week, I am beginning to wonder if he knows any more than I did. Once again, I will post the results if I get it back running... if I don't get it back running I will post the problems and hopefully someone will have a solid answer to what may be wrong.

Tom400CFI

Definitely give us an up date. Frankly, no one is going to give you a "solid answer". All you'll get is guesses, as you may have figured by now. What we CAN do, is clearly understand the symptoms, and then start going through a diagnostic PROCEDURE, that will eventually reveal clear and "solid answers"....w/o throwing parts and money at it.

HughG

Finally got my car back today after a week and a half. Turns out it was a two part problem, the fuel pump was only producing 6 psi and I am told it needs to be between 8-13 psi. The second problem, which was what really made it run like crap, was the distributor. It seems someone (actually a place that restores Corvettes for a living) put a distributor from a 1982 Corvette in it, and this didn't work. The mechanic bought a new one and put in it, timed it, balanced the injectors (not sure what that even means) and also reconnected several wires he said were disconnected behind the dash. Car fires up now, doesn't bog down and runs without misfiring. I can now drive slow speeds and not be embarrassed by all the popping and sputtering. The total bill for a new fuel pump, new distributor, oil change (was worried about gas in the oil so had him change it before I drove it home) came to $660 in parts and labor. I guess that wasn't too bad.

Thanks for everyone's help. If I had more time and did not actually need the car to drive everyday we probably could have figured it out. I still have lots of things to do to this car but at least now I can drive it while I do it.

Tom400CFI

That is great news! $660 doesn't sound bad for what got done to it. I'm glad to hear that it is running again! PING us for any more help you may need.

As WAYNE said...it sounds like your car was "TASSisized".

CFI-EFI

That is "Tas***ized". Or possibly, "TAS***ized". You have to clearly identify the source for the need for the bolded part.

RACE ON!!!

HughG

Couple questions. You said that your car was 130 hp stronger than stock, how did you obtain this? Complete overhaul of the engine or was there things you could do to the stock engine to boost the hp? When I first got this car I wasn't really too worried about the speed but I have some smart *** I work with with a stock Mustang that has 260 hp and I would really like to give him a run for his money.

After all the work to my Corvette I finally had to break down and buy new mufflers because mine were leaking so bad, once under there I saw that the pipes are in horrible shape. I cut off the cat and patched up the pipes and now the leaks aren't there but I'm suddenly getting 13 mpg! Even before the best I was getting was 17 mpg. I had an 84 before and got somewhere around 22 mpg. Why would fixing the exhaust screw it up so bad? I plan on buying dual exhaust in the near future, not sure if that will help or hurt.

85vette-84vette

Wow, God has spoken :rof l:

HughG

???