Slight hesitation upon throttle blip @ idle?

Digitalchaos

Registered User
It seems at idle if I apply the throttle very fast and with moderate pressure (half way) the engine will sometimes slightly hesitate before reacting.

From my conventional knowledge this seems like a tuning issue, spark plugs. However, those are new within several thousand miles.

Anyone think this is significant?
 
Digitalchaos said:
It seems at idle if I apply the throttle very fast and with moderate pressure (half way) the engine will sometimes slightly hesitate before reacting.

From my conventional knowledge this seems like a tuning issue, spark plugs. However, those are new within several thousand miles.

Anyone think this is significant?



What Kind of Plugs? How old are your wires? I would point to either one of those areas.


Chris
 
same

i want to jump in because im kinda in the same boat here, my car does it too, execpt it only does it ONE time after a cold start up, if i apply the gas to about 0 psi, the car boggles for a second. but then it's fine, never does it again, i think it's a fuel issue, feels like the car cant get enough gas and then it does, it wont do it if i rev it slightly during idle which is why i think it's a fuel thing, feels like once the fuel gets going it's fine, replaced fuel filter, no luck, plugs and wires are pretty new, hopefully we can find something out.
Damon
 
Try connecting a fuel pressure guage to the fuel rail and drive the car.
The pressure could vary between 30 - 40 psi. with a stock pump.
Maybe the throttle position sensor is on its way out. :eek:
Does the Check Engine light ever come on?
 
No check engine light or codes. Plugs/wires are Autolite dpp7xx (can't currently remember, they are correct) and Motorcraft. Both are within a few thousand miles.

I do suspect my injectors may be leaking through, and have recently used 2 bottles of Techron additive.
 
more hesitation

Well i hope you guys have fixed your hesitation problems by now, i see this thread is a few months old.

I've got exactly the same problem. Its a 91 Auto, dip into gas from a stop and there is no-go for a tiny second. there is no matter of temperature. easy take offs make you think there is nothing wrong with it.

here's where i've been and whats going on.

engine rebuild a couple years back, car isn't driven daily and don't recall when this problem started.

tried cleaning TB with a rag, i still have the sticker that says "do not clean..."
exchanged: TPS, IAC, MAF
New plugs and wires, old ones weren't looking too good.
Sealed all IC tubes with teflon rings from Tbird88.
Found deteriorated vacuum line between PCV pipe and vacuum hose that goes towards fender. put clamp on side that connects to inlet plenum.
No EGR on this car
I have replaced air filter, and have a fuel filter which i haven't put in yet.
Replaced gasket from intake elbow to intake manifold
Replaced TB gasket, and resealed inlet plenum to rear of SC.

With a rubber hose in my ear (haha) i could and still do hear some "air" sound from the back of the SC. I thought it was from where the inlet plenum connected to SC, thats why i resealed it (used IndianHead gasket sealant). After i put it all together sound was still there so i compared to another SC and heard the same sound, that car runs fine.

I've got no KOEO, KOER, or KAM codes.

O2 sensors are newer.

Car idles at around 17-16 inches of vac. in park and about 13 or so in drive.
other than this issue car runs very well.

I'm up for smog, (california) about 2 weeks ago. I think it could pass, but almost don't want to spend the money because i don't have it.

thanks for any help
jim

EDIT: almost every item was changed separately and throughout I noticed about no change at all.
Also at one point even the ECU was exchanged.
 
Last edited:
Kevin, I pulled my injectors and they were pretty clogged in the tops where they go up into the fuel rail. Have you ever taken them out to have them cleaned and flow tested? I'll have my set in on Wednesday, if they get here early enough and I hope that cures my problem.

I also had an intake issue, but I think the injectors were more of the problem.

Good luck!

David
 
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