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84 still wierd

E

evolution

Guest
Lingering problem here....
(some of you may remember this one, I forgot what some of the replies were too)

So..On acceleration (3/4 throttle to WOT) it just bogs instantly, kind of like hitting a wall. On brief taps it is hesitant for a sec then it revs nice. It has new wires, cap-rotor, Hypertec stage II, mufflers(stock), cat checked out fine, EGR and a pretty new ECM.
It almost sounds like a slight backfire as well but Im not sure.

Im kind of running out of ideas. Anyone else have any input?
 
C

c4ever

Guest
I would attribute to an air/fuel problem. Have these been checked?
 
E

evolution

Guest
Umm

I personally dont know how to check that.

It just seems wierd how abrupt it happens.
 
E

evolution

Guest
.....

I was going to install a K&N air filter but $80 is a big hit. Do they make that big of a difference on a crossfire?
 

Radar

Well-known member
Joined
Oct 23, 2001
Messages
200
Location
Oconomowoc, WI
Corvette
1989 Medium Blue Metalic Convertible
Does your crossfire have throttle position sensors? I would check them or something like that. You say the cats are clear so that shoots my other idea.

I assume that you checked the fuel rail pressure and that is okay.

The other thing I would check is a vacuum leak. Are all of your hoses in good shape? I would think your idle would be bad if you had a big vacuum leak but with all of the ecm stuff the ecm may compensate for the excess air at idle , so perhaps you should scope this out

Radar
 

BigRed

Well-known member
Joined
May 23, 2001
Messages
948
Location
Edmonton
Corvette
1985 Bright Red Rocket
I agree with the Postion sensors as well from my limited knowledge thats what it sounds like.

As for the K&N Don't expect a HUGE difference if one at all, It does give you power dont get me wrong but the REAL reason I like em is they nearly last forever with proper maitenence Just clean, let dry, and reoil. No more buying paper filters for 10 bucks

Also if you really want some power out of the K&N FEED IT! Take out your Air filter box and take a Jig saw or Cut out router and open it up (Just leave the strengh of the frame behind) Or you can just buy this for say 60 Bucks out of Ecklers.
 

Paul G

Well-known member
Joined
Aug 27, 2001
Messages
200
Location
Griffith, IN, USA
Corvette
96 CE LT4 Convertible
I had a similar problem with my 88 TPI. Engine would bog when the throttle was cracked open quickly. I did a complete tune up and cleaned the injectors. It ran better but did not solve the problem. Turned out the ECM was not recognizing input from the TPS. Bad ECM. Only way to find it is with a scan tool and watch the input value from the TPS change with throttle position. Mine never changed even though the TPS and wiring in to the ECM all checked good. I had to replaced the ECM and the problem was gone.

May not be your problem, but something to check.

Good luck
 
E

evolution

Guest
Hmmm...TPS

Perhaps that could be bad.

Also, I checked for codes and nothing pops up. As for Fuel rails, the crossfire does not have them....well to the best of my knowledge. If it does, they are hella small.

I do have a spare ECM laying around that I was told was still in perfect condition. Come to think of it, the problem may have started after the new one was installed.

Any do's or dont's I should know about with the ECM?

Ahhh.... one last thing. Is there a chance that the ignition module (the part where the key goes in, I think) could be crappy?
 
E

evolution

Guest
Air box??

Is this applying to the TPI engine or CFI?
The CFI just uses a cowl induction of sorts and I dont think there is a way to improve airflow from that. If there is I want to know.
 

Paul G

Well-known member
Joined
Aug 27, 2001
Messages
200
Location
Griffith, IN, USA
Corvette
96 CE LT4 Convertible
Re: Hmmm...TPS

evolution said:
Ahhh.... one last thing. Is there a chance that the ignition module (the part where the key goes in, I think) could be crappy?

If that was the case you would have starting problems more than drivability trouble I would think.
 
E

evolution

Guest
True but.....

I had a 78 Chevy van that had a few horsies under the hood ;) and I would play around corners and stuff. Once in a while the d@mn thing would cut on me when hitting a corner----bad news with power steering--- turned out that it was the ignition module. I was just hoping that it could be something more simple than that.
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
Sounds a lot like a stock 84 fuel pump that can't keep up w/ pressure! A very common problem. Replace w/ 85+ unit. Use ACDelco, not the pep boys stuff! Also buy new strainer, without warrenty on pump will be void.

Marck
 

vettl83

Well-known member
Joined
Apr 26, 2002
Messages
175
Location
Casper Wyoming USA
Corvette
91 L98 Quasar Blue, 91 ZR1 Red, 07 AO Coupe
You may want to check the voltage at the tps if I remember correctly I believe it needs to see 4.5 to 5 volts. They do make tps enhancers that are a direct plug into the tps. I believe they call them throttle performance switches. I have seen them in Mid-America catalogs. Good luck
 

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