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Have a CrossFire that in general runs GREAT, I just fixed intake coolant leak between manifold and head it now has all new gaskets. This problem was prior to the work and I though was just a vacuum leak now all new gaskets and no vacuum leaks it still does it. In park or N it revs great no issues at all even when chop the throttle. The problem is as soon as put in drive or reverse and I chop the throttle anywhere from 1/4-1/2 way just push it and let it up instantly it will move or jump then instantly cut off die. When in gear or reverse basically with a load If I slowly push the peddle it is fine car has no issues and is normal, but if not moving or rolling and just chop it bam dies out. If I floor it or give it 1/4-1/2 and hold it it’s fine. Only when I chop the throttle in gear it always dies out I am thinking it’s the idle air control valve/s but I am not sure. I know one is in the throttle body down in the valley and you can see the nipple stick out slightly from the hole when it’s running. Have not checked to see if both TB have one or just the primary, if it is not the IAC what else could it be or what do I look for. Never have had any vehicle ever do this dying with throttle chop in gear only, any help or replies are greatly appreciated and thank you for taking time to read this post.
Best information I got on my 82 Crossfire was from Buccaneer and Tom400CFI.
I don’t know if they hang out on the C4 pages, but you may try messaging them directly just in case they stay in C3 land.
have you checked for codes maybe do a fuel pressure test. Is the air filter clean check tps voltage maybe coolant temp sensor or map sensor. I miss my 84 Tom400 can be super helpful with crossfire.
I'd be interested to hear what Buccaneer has to say about this one, but I had a similar problem with mine, although it was a stick...it would do it when I was decelerating, injectors off, and if I pushed in the clutch right before the injectors would cut back in....it'd flood itself and stall. If I waited until after the injectors cut back in, then pushed in the clutch, it was fine. Anyway, my car was modded and I attributed the behavior to the mods. MY "fix" was to install a vacuum referenced fuel pressure regulator, which lowers fuel pressure when there is vacuum in the plenum...like when chopping the throttle. It worked great, and completely eliminated the stalling issue.
I think that you're right to check the IAC's though; if they or one (there is one in each TB assy) isn't opening, I can for sure see how that would contribute to a rich/stall situation when chopping the throttle. You've got a bunch of gas in the plenum from the accel, then you cut the throttle (and air)...all that puddling fuel vaporizes easy in a vacuum and it's flooded/stalls.
Thanks for all the replies so far have checked everything besides both IACS. All sensors and vacuum are dead on I have not checked FP from what I can see and researched you have to tap one in the feed line and I have not done this.
That's true about checking FP. The rubber line between the frame and the engine is probably the easiest/fastest way...many have brazed a schrader valve onto the fuel line that runs from the front TB to the rear TB as a more permanent solution.
Spec is 9-13...they typically "like" closer to 13.
When your engine stalls, have you confirmed that it is, in fact, from flooding? Does it start faster after stalling by using WOT while cranking?
Well, it doesn't sound like it's over fueling like mine was. Can you have someone (carefully) goose it in gear while you're (carefully) under the hood w/the air filters off? Watch it and see what happens?
Timing is set at 6 I have played with 8-9-10 and she LOVED IT, at 11 she got a slight ping so dropped one degree and she was awoke lol. Since having a issue I put it back to 6 degrees for time being. Yes I can jump under hood safely and watch but what am I looking for exactly. I know when I am under hood and the gas gets hit it’s gonna die out lol so what do I watch for sense right now I have NO CLUE or what’s going on? I just bought a fuel pressure gauge (a mr gasket 1560)
ima splice in tomorrow.
I'm not sure what I'd watch for...I'd mostly be looking for IAC action (loud sucking from both inlets) and what are the injectors doing? On mine, if I'd done what you're doing, they'd DUMP fuel for a second....flood it and kill it. So I'd just watch and see what it's doing.
From the "olden days" accelerator pump would add extras fuel when accelerator pedal was pushed quickly.
With fuel injection, the Throttle position sensor (TPS) takes place of accelerator pump
When swept quickly, commands additional fuel due to additional load -- TPS base voltage "plays little" here
Did you run a "scope check" of the TPS?
or at a minimum look at the voltage on a DVOM when sweeping the TPS
Should be a smooth increase--not jagged ---when sweeping TPS, press on pedal inside car not from under hood, throttle linkage at times will cause a "twisting" of the TPS and ONLY case issue when swept from inside (been there !!)
--scan tool is "too lagging" for this test
What are the Manifold Absolute Pressure (MAP) sensor readings? at idle and higher RPM
MAP adds fuel when under load--
Is vacuum line connected to MAP sensor?
Is there about 17" of vacuum at idle at the MAP connection?
Does vacuum reading decrease as throttle opening increased?
Does MAP change reading/s as throttle position is changed?--Scan tool or DVOM
Fuel pressure check always an excellent idea on Cross Fire--would discount here as "good" prior to repairs
Would focus on things "touched" when doing repairs
So at idle it runs at 10PSI as soon as give any gas or revs it drops to 6-7 is this a issue? I have some videos ima try and upload of it all. Since can’t upload the 5 second videos I will add my YouTube link to my channel after I upload the videos.
Last edited by CrossFireGuy; Jun 3, 2022 at 06:20 PM.
The links to the vids. Showing fuel pressure and throttle bodies, also fuel pressure as revving then the car in R and D stalling and then chopping throttle in N or P the same as in D or R and not stalling.
84 Crossfire help
