When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I reviewed my FSM & tried to do what I can without a scanner (which I’m looking to buy) on my 89 Corvette to resolve the hesitation I’m getting when I mash the gas pedal or even blip the throttle.
Throttle Cable:
I’d read once or twice about adjusting the throttle cable but my searches only turn up info on auto trans & nothing for s manual trans. So can it be adjusted or am I barking up the wrong tree?
IAC & TPS:
I did the process the other day but couldn’t do it with the distributor set timing unplugged as I couldn’t keep it running. I did my best guess on ISC but with out a scanner I could only guess at 450rpm off the dash tach. The TPS was kinda a cluster f’k as readings were jumping around with the new TPS i installed & the top hole buggered up which stripped the bolt. Ultimately I gave up
& reinstalled the OEM tps, set it to .54v & quit. In hind sight I did find s spot in the FSM which recommended the vehicle be at operating temperature & absolutely have distributor set timing disconnected, so it looks like I will need to do this again.
The Corvette had a better idle but still has a noticeable hesitation. Any further direction id very much appreciated!
if computer getting bad readings from TPS there will be a lag in fuel adjustment. Sounds like that is likely here. Can you slowly give it pedal and not bog vs hitting hard and bogging down?
if computer getting bad readings from TPS there will be a lag in fuel adjustment. Sounds like that is likely here. Can you slowly give it pedal and not bog vs hitting hard and bogging down?
Yes, when I roll into the throttle I don’t get hesitation, just when I mash the pedal, which I often do.
Well this sucks. I went through the IAC adjustment process but cannot keep the car running with the distributor set timing plug disconnected. No matter how slowly or how many times I drop the rpm down, she wouldn’t stay running. Idle Rpm is a 9 (900) on the dash. I can play around with the idle screw when she’s running & raise or lower the rpm but as I’ve read & been told that’s not going to set it right! Aghh!
You can raise your idle up to 1000 RPMs if you need to keep it running to set the initial timing. Once you can get your initial timing then you can drop your idle RPM and recheck the timing. Your hesitation could be several things going on though. First how much hesitation do you have. Is it a half second or 5 seconds from when you step on the throttle?
You can raise your idle up to 1000 RPMs if you need to keep it running to set the initial timing. Once you can get your initial timing then you can drop your idle RPM and recheck the timing. Your hesitation could be several things going on though. First how much hesitation do you have. Is it a half second or 5 seconds from when you step on the throttle?
Ok, how does the car run though, does it miss or is it running good? You said when you rev it though, if you are in nuetral and you rev it, does it take a half second to rev after you have already hit the accelerator?
Ok, how does the car run though, does it miss or is it running good? You said when you rev it though, if you are in nuetral and you rev it, does it take a half second to rev after you have already hit the accelerator?
Most of the time it seems to run well, no misses, etc. it’s a manual so I’d rev in neutral & yeah it’s a slight hesitation 1/2 second or less & not a crisp response to the pedal. I’ve not tried a double rev, if that’s what you’re asking.
Ideally a scanner would probably tell you what's going on....
But absent that, you can test the TPS sensor with an ohmmeter. (if you haven't done this already...)
Put the probes across the blue and black wire terminals (will need to disconnect the harness connector). Don't need to turn the key on.
Then simply move the throttle and watch the ohmmeter. The resistance should change the millisecond you move the throttle, and it should move smoothly and linearly. If you get erratic readings, your TPS is likely going bad.
Other things to check would be your fuel pressure.
Most of the time it seems to run well, no misses, etc. it’s a manual so I’d rev in neutral & yeah it’s a slight hesitation 1/2 second or less & not a crisp response to the pedal. I’ve not tried a double rev, if that’s what you’re asking.
Try checking your timing, once that is set you should be good. So on a L98 a hesitation is normal, a half second is minimal if it is a half second. Remember its a Tandy 2000 equivalent that is running the engine.
02-02-2024, 11:12 AM
Hesitation Issues
