Hi,

About a year ago I bought a 84 corvette not knowing anything about corvettes and I am now paying the toll. In july of 09 I had a jasper remanufactured engine installed into my car and about a month later my transmission gave out so I had a rebuild. After all the money that I have spent the car runs no differently from when I first purchased it. I have taken to several different shops in the Orange County, CA area and nothing seems to get fixed. I am on my last nerve with this car and Im thinking about selling it if I cant find a decent mechanic, unfortunetly I am not car savy what so ever so I cant fix it myself. My main problem with the car is inconsistant power, some days it drives perfect and other days I want to drive it off a cliff because it runs so poorly. What other parts or services would you recomend doing to this car? And if anybody lives in the Orange County, CA area do you know where I can find a mechanic that will do honest work? I have had a few other parts replaced other than the transmission and engine but I would really like to hear what you all think. I appreciate all of your guys help and I look forward to the responses. Thank you.

-Travis

 

Most mechanics don't know how to work on 84's, even though the injection set up is really the same as a chevy truck but double.

Please describe the problem a little more in depth, is it setting the check engine light?

http://www.crossfire.homeip.net/ wil give you a wealth of information. A lot of the non 84 owners on here will just give you grief and not offer any useful info.

I am sure it is not a severe problem, it is a simple car to work on if you know what you are doing.

Shawn

 

Since the motor was replaced I'm guessing that the computer is not adjusted to running with it. This is a guess and hope this helps. Sorry about your bad luck. I hope you can get it running good again. 84s are great Vettes.

 

J and D corvette. They are our C4 tech sponser. Bellflower Ca. They have a web site. Been in business since 1958. Highly recommend. They do it all. Parts and service.
Corvette Mike

 

You need to find a Corvette mechanic in your area to give you a hand. I don't think you have a major problem. I'll bet it needs a few adjustments from an experienced hands on Corvette guy. Those 84's really are good cars. They just seem to draw alot of negative comments from some guys who just don't understand them. If you give up on it and sell it, you'll probably then find out from the new owner that the problem was minor and you'll regret giving up on it. Good luck.

 

It could be as simple as you are buying poor quality gas. Use Shell premium for a couple of tank-fulls. Pour in a can of "Sea Foam" cleaner into the 1st tank.

 

Before I get started, I strongly advise you to learn to work on your own car. If you can do your own wrenching, a C4 can be kept running forever for a reasonable amount of money. If you have to farm it out everytime it hiccups (and it will, trust me)...it can bankrupt you. If you can't wrench, join a Corvette club in your area, make some friends in it that CAN wrench, invite them over and buy the pizza and beer and let them teach you. It will be much more rewarding to you as well....you will know your car inside and out, and won't be in constant fear of something breaking.

Back to my mantra.....

They need 3 things to run, and three things only.

1. Suitable compression
2. The correct mixture of fuel and air.
3. A suitably strong spark delivered at the correct time.

That's it. If those three conditions are met, they run. If one is missing or deficient, they either don't run correctly or at all. Your job is to find out which of the three has the issue and then narrow down why....and ultimately correct the issue. See how easy this is? But remember....TROUBLESHOOT, DON'T GUESS. Guessing is fine...if you have unlimited money and time, which if you did, you wouldn't be driving a C4 in the first place. WAY tooooo much guessing goes on here. Approach it in a methodical fashion and you WILL find the problem.

I would start with checking fuel pressure. NOT FUN ON A CROSSFIRE. There is no schrader valve like the TPI cars have....so you have to do one of two things. Put in a T fitting in the pressure line down by the fuel filter...or do what I did and build a port into the crossover tube between the throttle bodies....like this...




I took the tube and a low pressure gauge (0-15 psi) to a tubing shop, they charged me $25 to fit each with a fitting....now I can check fuel pressure in 15 seconds. I strongly recommend the same. You can pick up a gauge for under $20 at Harbor Freight Tools, and your tubing shop can crimp the fittings on it.

You should have between 9-13 psi on a Crossfire....really anything under 10 they don't run correctly. Hook the gauge up, turn the key on, and tell me what the gauge reads. It should rise to 9-13 for two seconds, then drop to zero immediately (Crossfires don't hold pressure). Hopefully you can get the car to stutter and check it during an event. It may have an intermittent fuel system issue....test when it's running like crap.

Run that test....get a friend to help if you can't do it yourself....and tell me what you have. If we lived close, I'd have your car running perfectly in an afternoon, and you'd owe me Dinner at China Bistro. You can always send it off to the shop Mike recommended....they have a good reputation....but get ready to open your wallet again.

Happy wrenching....let me know if you need help.

 

Oh...forgot to mention....leave the car running doing the fuel pressure test after you've done the Key On test. In fact, have the tubing shop make a long enough line on the gauge that you can tape it to the windshield, close the hood, and drive the car with it attached. This way you can see fuel pressure when you're road testing the car.

 

As always frizlefrak well said....

 

Are the 84s like the TPIs where a clogged fuel filter or bad O2 sensor will make it run like crap? With the car being 26 years old it could have been a very long time since either one was changed. A clogged fuel filter won't even throw a code and will cause odd things kind of like what was described.

 

Yes. And both fuel filters and O2 sensors are "consumables"....ie, maintenance items, and should be replaced regularly. But our fuel pressure test will also tell us if there is an issue in the fuel filter. A clogged filter will result in low (possibly intermittent) fuel pressure. Given that it's last date of change is unknown, it would be a good idea to change it now.

I'm a HUGE believer in troubleshooting.....that is, a methodical, process of elimination approach to wrenching. Testing each system, and either finding an issue or ultimately giving that system a clean bill of health and moving on. I've never liked the "spray and pray" method of throwing parts at a problem hoping something sticks. Very wasteful of time and money....neither I like to part with voluntarily.

I had a similar issue with my 84 last summer....intermittent poorly running engine. I quickly narrowed it down to one injector not firing all the time. Troubleshooting revealed that switching the injector wires made the OTHER injector malfunction instead, ruling out both injectors. Long story short, a few hours with a multi-meter testing circuits, I ruled out all wiring. The only thing left was the ECM. I replaced it with a used one that a guy on the forum sent me for free....problem solved. BTW...it NEVER threw a code....no check engine light ever. My only real hint was that it only replicated the problem when hot....heat creates electrical resistance...and a flaky injector driver could work fine cold, but not hot. Total cost to repair....$10 shipping on the ECM, and about 5 hours of my time.

OK....off my soapbox.

 

Could be the fuel pump as well.

 

Well I have an 84 myself with the crossfire engine. I agree with fraz. You have to learn it yourself. I have had mine since July of last year and I love it. The best thing about it for me is its not my daily driver. So, I can do work and if I dont finish or get stuck its ok. I have had mine run rough also. I bought it from the original owner. I had 89,000 when I got it. I tuned it up and replaced the plugs and wires etc. It ran better but I felt it was not as good as I thought. After reading from some of the guys here. I also replaced the EGR valve and I also replaced the O2 sensor. I bought all my parts online too. Both were original. Big difference. Car runs great for me. Starts up everytime, idles great and it goes like hell. I did all the work on mine also except for replacing the exhaust.

I enjoy working on mine and I love to read about how to do stuff for it. Its a great car and a great year. All those people who talk about the crossfire dont understand them or never had one. I got a GM manual on ebay for mine and it shows everything. And if I get stuck, I ask the guys on here and they all step up with ideas and solutions.
This place is better than any mechanic.
Take the time and have some patience. Its a good car and I think you will regret getting rid of it.
I know mine is stuck with me for good now.
I take alot of pride in my 84. Driving it around and people looking at it and they say wow, thats an 84?
Ya, its 26 years old and I keep her going. Thats the best compliment I could get. And mine is in excellent shape. Original paint and everything.

Hang in there and good luck.
Kevin

 

You really didn't mention if it is still a crossfire after engine swap. I agree in changing fuel filter (on passenger side by front of door) and changing O2 sensor(84 only has one on driver side by oil filter). This a cheap changeout even if you are not a well healed mechanic. These parts are overlooked a lot for simple repair issues. You may even have a loose connection on one of your sensors,it could be the intermittant part of your problems.
Good luck,
Woody

 

frizle, do you have a quick-change nipple on that t-fitting on your crossover pipe? or is the guage always on there like the kit from the crossfire web site?

 

Just a male nipple on the crossover tube, and a corresponding female orifice crimped onto the gauge's hose. There is a cap that fits on the crossover tube when the gauge isn't on.

This is the A number one mod I recommend for a new Crossfire owner.

 

is that valve/nipple setup a schrader valve?

 

No....just a port. You could just as easily put a schrader valve on, but the gauges are typically 0-100 psi. I wanted to use a low pressure (0-15) gauge.

 

thanks! I'll check it out! I got a guage setup from the crossfire site but it's always installed and the new cross-pipe didn't quite fit. tried to get the right angle but always popped a fuel leak at the connections when hot. would rather have a setup like yours and really like your idea of having a long enough hose to stick it on the windshield! appreciate your basic principles of troubleshooting! keep it simple and identify what is missing or different through each step. thanks!

 

I just cut the feed pipe between the two throttle bodies down to the straight part of the fittings and dropped in a 0-15 LB. guage run up by the master cylinder so when I am working on my card it is close to the drivers side. I will try and get a picture tomorrow of the setup. It's very simple and is always in line and working. my is running about 12 LBs which is pretty solid for the 84's. They usually run at 9-13. I hope this helps. by the by, use good quality hose clamps some of the cheap clamps won't hold very well.
Woody