hesitation ???

[zr-1assassin]

im getting a bit of a hesitation i guess is how you would explain it. when the car is at idle, and you floor the gas, it seems to stumble for about a second and then shoots back up. its like its going to die for just a split second. the rpm's actualy go down when you floor it and then right back up. i have tried pressing the gas pedal slowly to raise the rpm's and it does it with no problem??? this is in neutral or in gear taking off it does it. just started this a bout a week ago. anyone incounter this? any ideas where to look?:icon_scra

[zr-1assassin]

just went down and was tinkering with it a bit. i had the hood up this time and was flooring it from idle and its still doing it, with a little backfire to boot. and i can realy smell its running rich. there is a heavy gas smell on the exhaust??? i have a haibeck chip and i thought that laened out the f/a mixture??

[GrayZ]

my guess, injector's leaking.
not the greatest of news.
Are yours original?
either replace em soon.
or just....kill yourself. :mrgreen:

[zr-1assassin]

my guess, injector's leaking.
not the greatest of news.
Are yours original?
either replace em soon.
or just....kill yourself. :mrgreen:that would be my first guess too, but the injectors (ALL 16) were just replaced about a year ago with RC. and if it is the injectors.......i will kill myself $$$$:mrgreen:

[Jeffvette]

Think about checking your plugs.

[zr-1assassin]

Think about checking your plugs.just changed the plugs about two months ago...... it does still have the factory wires, with 36K on the clock. do you think the wires could be bad? i have a new set of acdelco's, just havent put them on because the plenum removal seems like a hell of a job. the local general wants $300 to change them and that just seems like so much i talked myself into trying it myself some day.

[cvette]

just changed the plugs about two months ago...... it does still have the factory wires, with 36K on the clock. do you think the wires could be bad? i have a new set of acdelco's, just havent put them on because the plenum removal seems like a hell of a job. the local general wants $300 to change them and that just seems like so much i talked myself into trying it myself some day.

It's not that big of a deal to pull the plenum. A wire change should only take about an hour! I'm booked this weekend but maybe next I can find my way to Joe town. I need to run to Maryville anyway to check the farm house!

Just for the heck of it reach behind the plenum and make sure the vac lines are still attached to the fuel pressre regulator and the map sensor.
I have seen backfires blow these lines off.

Charlie

[tomtom72]

I'm with the "check the wires" camp.:redface: Only because I swapped my OEM's out when I did my injectors. The car only had like 10K on it but the stuff was 16 yrs old. I don't know that time has much to do with wear on wires but ya never know. I'd ohm them suckers up just to be sure anyway....never hurts to be sure?

Another random thought crossed my mind. Could the TPS have a hand in the hesitation? I'm thinking that it's a rehostat type sender and what if it gets something funky on the continous contact? Maybe throw the scanner on her and see what's up with the signal???

Good luck with this!:thumbsup:

[ArcticZR1]

I have the same problem on my 91' I have no idea what it is either. Please post your outcome...that would be a major help. My car smells like it's running really rich after I put my B&B on. No chip...stone stock.

[BBBAD94ZR1]

I would take a look at the plugs and the gap, my cars did the same thing it was the plugs and the proper gap I used Ngk Irid. problems gone......
RAY

[zr-1assassin]

I would take a look at the plugs and the gap, my cars did the same thing it was the plugs and the proper gap I used Ngk Irid. problems gone......
RAYya, i was considering that as a poss. cause. what did you gap them at?? i think i gapped mine at .035

[zr-1assassin]

I have the same problem on my 91' I have no idea what it is either. Please post your outcome...that would be a major help. My car smells like it's running really rich after I put my B&B on. No chip...stone stock.i will keep you all updated! i talked to mark haibech yesterday and he said the exhaust smelling rich was absolutly normal. i have never had any other car smell like this so it does seem odd to me..... but if mark says its normal...good enouph 4 me!:thumbsup: and he said his chip (which i have), is designed to run it lean at WOT, not idleing it in the garage.:mrgreen: my next step is the wires and then the plugs again to make SURE they are gapped right. i'm useing ACDelco #5 by the way, may switch over to the ngk and give them a try.

[ArcticZR1]

Thanks for the reply. I hear from everybody the NGK plugs are great. I have splitfires which I hear are not so good. What are the best wires to get?

[tomtom72]

Chris, I see you have a 90. I'm using the stock GM replacement for the FR2LS plugs that came in the 90's. I don't remember the # but it's just a std plug...no trick stuff, no rare earth metals & they work fine but I have stk exhaust and stk chip. Oh, yea the gap is 0.35.

If Mark says the "rich" smell @ idle is okay then my thought is the possible lack of back pressure @ low rpms would/could cause a bit of hesitation?? I would think that electrically speaking if the wires were toast that would show more at high rpms....bad cores and higher loads = poor performance but not at idle unless they were "leaking" and cross arching??? Hood up in a dark garage & no clam shell lights may be a simple test? Or grab some wires and shake them & see what happens?

FWIW, when I replaced my OEM wires I bought a set of Magnecore's off e-bay for like $150 shipped. I like them, they work. I'm sure stk replacements work also for a lot less $.:redface:

:cheers:
Tom

[GrayZ]

Only other possible cause i can think of...
you're car got a good look at YOU in
the rearview mirror, and if that is the case.
try driving with a disguise?!! :mrgreen:

[zr-1assassin]

Only other possible cause i can think of...
you're car got a good look at YOU in
the rearview mirror, and if that is the case.
try driving with a disguise?!! :mrgreen:now just because thats what happened to you does not mean it will happen to others. i think you have consumed one to many slices of pizza and its starting to effect your brain.its already effected your body:mrgreen:

[ArcticZR1]

RESOLVED - I just changed my plugs this morning. I got the NGK iridiums. The NAPA guy said they were pre gapped. After I swapped them out there was no more stumble. The car seemed to run alot better and smoother. I only have 22k miles on my car and these are the 3rd set of plugs. The split-fires I took out looked like crap. I also put anti-seize per Jeffvette...what a pain the passenger side closest to the firewall was. Be sure to have a magnet!

[zr-1assassin]

RESOLVED - I just changed my plugs this morning. I got the NGK iridiums. The NAPA guy said they were pre gapped. After I swapped them out there was no more stumble. The car seemed to run alot better and smoother. I only have 22k miles on my car and these are the 3rd set of plugs. The split-fires I took out looked like crap. I also put anti-seize per Jeffvette...what a pain the passenger side closest to the firewall was. Be sure to have a magnet!ya, i think thats going to be my next move. thanks for the update! and i know what your talking about on the #8 plug...:mad:. i also resorted to a magnet....worked well!:thumbsup:

[BBBAD94ZR1]

When I used stock plugs .30 ngk ir's no gap, they make a world of difference.
Ray