LSV has a new hickup

[rkreigh]

just crested 94K miles and the car has developed a very intermittent low rpm "stumble" at light throttle (and very randomly) the car will hesitate and it feels like it goes into 6 cyl mode and stumbles I give it a bit of throttle and then it stops the stumble and pulls cleanly and then stumbles again.

I can't get it to do this consistently. I thought it might be a bad tank of gas, but I've had it continue. time to break out the factory service manual and go through the trouble shooting charts!

I'm thinking a coil pack might be failing or maybe even the injectors

never fiddled with this car much, just drive the wheels off it!!!

I'll start with checking the plugs as they are older IT22 but they seem to last forever. I've probably got 20k miles on them by now but they really last a long time and the plugs are probably ok (I'll change them just for grins, a cracked plug can do this too)

let me know if you all have any thoughts or have had this. it always seems to clear it's throat by 2500 rpms and WOT has always been the cure :o

[WARP TEN]

just crested 94K miles and the car has developed a very intermittent low rpm "stumble" at light throttle (and very randomly) the car will hesitate and it feels like it goes into 6 cyl mode and stumbles I give it a bit of throttle and then it stops the stumble and pulls cleanly and then stumbles again.

I can't get it to do this consistently. I thought it might be a bad tank of gas, but I've had it continue. time to break out the factory service manual and go through the trouble shooting charts!

I'm thinking a coil pack might be failing or maybe even the injectors

never fiddled with this car much, just drive the wheels off it!!!

I'll start with checking the plugs as they are older IT22 but they seem to last forever. I've probably got 20k miles on them by now but they really last a long time and the plugs are probably ok (I'll change them just for grins, a cracked plug can do this too)

let me know if you all have any thoughts or have had this. it always seems to clear it's throat by 2500 rpms and WOT has always been the cure :o

Hi Ron--
I run into this occasionally and a few months ago Marc suggested that O2 sensors are a likely cause on mine. He said he did not change them when he did my engine work because they looked and worked fine (they had about 25,000 miles on them at the time). But with the engine work we added headers, removed catalytic converters and richened up the mixtures a bit (I think) so maybe that affected it. I have since bought new O2 sensors but have not installed them, and naturally have also not had the stumble for quite a while. Just before takeoff I also have an old habit of tapping the throttle repeatedly a bit like we used to do to clear carbon in the old days. Maybe I have been loading them up a bit and confusing them. Like your situation, it always clears quickly once I get going. Anyway, when I get a chance I will probably replace the O2 sensors sometime this winter. --Bob

[RussMcB]

If you decide to try new O2 sensors I bought a pair then did not use them, will sell for a discounted price. I think they are the good AC/Delco model recommended somewhere here in the ZR-1.net forums. If interested, send me a PM and I'll confirm.

I also bought some new coils via ebay but ended up using some others. I'll sell them cheap, too.

[rkreigh]

good thought. I used to check the O2 "cross counts" to see when they are getting lazy before they code.

the LSV runs pretty pig rich at idle due to the cams and my bet is that they are due.

I'm interested in the sensors

I'm in Alex VA 22310 please PM me a price! thanks.

[XfireZ51]

...

the LSV runs pretty pig rich at idle due to the cams...

There are ways of dealing w this.

[Z51JEFF]

About 2 weeks ago my 91 did the same thing. While sitting at a stoplight the idle dropped and I could hear the cam chains-flywheel knock as the car seemed to be running on 6 cylinders. Brought the revs up and car was fine,drove normal. Did this for about 10 minutes then it hasn't happened since. I too was thinking coil dying or injectors. The 02 sensors are fairly new Bosch. When it was running like this I kept waiting for the CHECK ENGINE lite but it never came up.

[rkreigh]

check engine light cam one, antenna busted, and the service ASR light came on.

I think it's feeling unloved or cold or something.

I'll pull the codes and see what's going on

interested in the sensors and the coils!

[RussMcB]

interested in the sensors and the coils!PM sent.

[rkreigh]

great deal

sent the paypal $$$

thanks!