Is there honestly such a thing as a smooth, stable idle with Cross Fire Injection?? Had plugs, cap, wires, TBI replaced and adjusted, two new sensors on both throttle bodies...still idles fior ****...high, then low...all over! And no, No vacuum leaks ! Had SEVERAL people in the know tell me put an intake and carb on it !! Very discouraging !!

 

Your missing something. Yes there is a such a thing as a nice smooth idle with CFI.
At the end of the day it's just basic throttle body injection, there's just 2 throttle bodys.

 

And what AM I missing ??

 

OK, exactly, getting angry at it isn't helping. It's just a 80's Chevrolet with basic throttle body injection.
That said. There are some parts of this system that are now difficult or impossible to uptain.
Vacuum leaks inside the lifter Valley can be very difficult to chase down. Fuel pressure that isn't holding absolutely steady can play with your head.
Throwing any codes? If so chase them down. If not think of the things that cause trouble that do not throw codes. Like fuel pressure (13 PSI?). and Vacuum leaks that are hidden inside the engine. Properly working PCV system?

 

Lotta possibilities....thank you Sir...

 

There are many tricks the guys with CFI use and the one thing I hear the most about is the fuel pressure that is getting to your throttle bodies. They have a very special need for the just right amount fuel pressure to make the engine purr. When you have 2 throttle bodies on the same engine that gets a bit confusing.

CFI guys are needed here....

If you don't have a portable Air/Fuel anylizer then it could be more difficult. I would start with a fuel pressure gauge and verify that you have met the requirements for the engine. You might want to be sure that your O2 sensor is in good working shape.

A carburetor and an intake would make your C3 worth less than a comparable CFI C3. It might make it more usable but that is still harder than just fixing the Crossfire system. Fuel injection is really not that complicated and that CFI system is decades old so we should be able to make it work.

There are 12 second CFI C3's on this web site... You need to speak with the CFI Experts as they know all the tricks. Do Not Underestimate the CFI engine as it works and works well when set up properly.

 

Thank you Sir....

 

GM kept that system for two model years only (82 & 84) because it was awesome and the engineers did such a great job that the buying public and the warranty bean counters at head office loved it, right ?

Put a carb on it.

That being said, we have 1-2 masochists here that may help you out if they see the thread. Good luck !!

 

Yes, the CF will idle just fine when working properly. When you say "adjusted" did you balance the TBI's? Coolant sensor and MAP good? Check the EGR and EVAP? Any difference in idle in open vs closed loop?

 

That stuff is way above my ability. Problem is finding a tech to work on a 40 years old system that wasn't worth a **** when it was new!! Can't keep throwing money at it...spent enough already !!

 

There's no reason that a CFI system should have a rough idle. Something is wrong. But 12 seconds ain't going to happen with the stock intake. A Renegade or heavily modified CFI may get you there. It's a poor design and inefficient. The only reason to keep a CFI if you're into originality. Otherwise dump it for a more efficient induction system. Don't overrate CFI, it ain't that good.

 

Any Gen 3+ junkyard truck engine will turn a C3 into a 12 second car, and have a smooth(er) idle.

 

From the get-go of buying my 82, that's the one thing my crossfire did fine was idle smooth. Just really fast idle until the vacuum leaks were fixed and a few other things, but that's another story. What idle RPM range you see?

Already a lot of valid points to check in the previous posts.

So, if I'm reading it right, did someone actually replace both TBIs? Rebuilds or did they rebuild them? And I'm assuming the IAC motors were changed as well if those are the two sensors.

So then, I wonder how they did the fuel pressure regulator adjustments, the balancing of the two throttle bodies and the minimum air adjustment, then the throttle position sensor (TPS) setting after. Or were the TBIs just rebuilds taken out of the box and bolted on? I guess I'm wondering if your mechanic is experienced in these units. The previous owner of my car told me about all the supposed experts he took that car to. It's clear that the only thing they did was jack up his wallet and flush it out.

Some other thoughts:

Does the engine idle any less rough when cold or warmed up? Does the engine warm up to 195F on the gauge, or does it only rise to a lower temperature?

Maybe something you can do quick and easy: with the air cleaner housing off and set to the side (and the vacuum hose to the Thermac on the air cleaner housing still connected to the throttle body) start the engine. Now does the fuel spray look like a nice, even shaped cone, or is it dribbling fuel?

Did they mechanics tell you about how they set the throttle position sensor (TPS) and the voltage reading? Was the TPS changed?

How about the value of the measured fuel pressure at the throttle bodies? Did they advise that info?

How did they do the timing after changing all the ignition components? What I mean is, while timing the engine, did they temporarily disconnect the connector (located by the distributor on the driver's side) that has the brown wire that leads to the ESC module? Trying to time the engine to the stock 6 degrees with that connector still connected may cause some real problems.

Fuel filter ok or plugged? When was it changed last? I suppose it would really have to be plugged.

Weak fuel pump?

Is the CEL light on?

 

Meaning no disrespect but IMO this is not correct. The 82s already go for less than say an 80, even the sometimes screwed up 81s bring more, only plus is the 700r4. Originality means nothing when it comes to the crossfire and the older it gets the harder parts are to find and even harder to find someone who knows anything about it. Even the collector editions have come down in price... People know the crossfire issues and are shying away from them more and more. I have never met anyone who said something like...gee I wish I had a crossfire engine...never!

There is more to it than just slapping an intake and carb on it, the TV cable needs a special bracket, fuel regulator, transmission lockup for 4th gear....I'd get rid of the Cat and go true duals for exhaust....Make sure it fits under the hood.... But once done you can go to any decent Hotrod shop to get service...and you will have more confidence in your car...

60

 

OK, so, here is the real truth here. A. The OP has no real working knowledge of his car's system. Bummer perhaps, but true for a lot of people.
And B.
For reasons beyond my comprehension he cannot find a mechanic that understands a early, basic fuel injection system.

So, He has 2 options. One. Buy a factory service manual and learn to understand and repair his own car. (This may be time consuming but is extremely rewarding).
Or Two. Look for a mechanic over the age of 40. That really should be all it takes. This really isn't a complicated engine management system.
You have stated that you have replaced sensors and Throttle body's. But didn't explain why.
where these things tested and proven to be faulty? Or was it, hey, let's try this! If it was the latter. Pretty hard to feel sorry for you. Just throwing parts and money at the problem without an understanding is likely to cost a lot and fail. And continue to fail.
The, ... but my buddy's car it was the.......
method of diagnostics. Is very likely to cost heaps and lead absolutely nowhere.
My best advice. If this is all way above your pay grade. Buy a factory service manual and a few tools. LEARN! It's a Bloody hobby!
Or, buy a modern car. And give up.

 

Actually, the work I described was performed at a dealer. The tech was supposedly familiar with this "system" Replaced and tested TPS, not TB's... my mistake.... And both IC's.. No codes.... I don't have the time or interest in a factory manual.
to repair the car. I guess this forum is designed for someone that is. Simply looking for some insight and there is certainly plently of that! You must be retired with lots of time?. And I'm certainley not looking for you or anyone else to "feel sorry"! ...Beyond your comprehension?? Really?.. I actually had techs laugh when I asked them to take a look at it! I did finally find the guy at the dealer that seemed knowledgeable and willing to look at it..., maybe he did not go far enough... I do not know. It was better but not graet when I got the car back. As i said earlier, I am done throwing money at it! Like a responder said earlier in the thread, this sytem is wonderful and GM kept it for TWO years because it was! Anyway Thank you for taking the time to respond at all...

 

If you are paying someone else to do all the work, and you don't live next to @Buccaneer, I'll double-down on the LS swap solution.

Pay someone to do the swap (I've seen quotes of $12K or more, but whatever), and use OEM parts whenever possible, including the ECU. Once complete, you'll have a "modern" (early 2000s) engine in a C3, and can take that car to any garage to be serviced. Is there a garage in town with a bunch of Silverados parked out front? Start there.

 

Well said !!

 

Whatever you decide, don't go to a dealer for repairs. The mechanics suck and the service writers are a-holes. Any mechanic with half a brain with the skills to repair anything more than a flat tire has most likely moved on from working in a dealership.

 

I hear ya,,, the dealer tech was the only one that I could find to even look at it.....