Corvette missing uder light throttle

[Mr Genn]

Hi all, sorry if this has been covered before but kind of getting desperate. I live in England which makes it hard for a garage to look at my car as they haven't realy got a clue. I have a '92 LTI all stock with 50,000 miles on the clock, i replaced the OPTI with a MSD one last year due to the car missing and making a pinking noise when under hard throttle, everything was great for about 6 weeks when the car started to miss fire under light throttle this time, if i give it a foot full on the gas i would end up leaving my tires on the road and probably getting a speeding ticket. so i kind of lost interested with the car it spent 8 months in the garage under cover till now.
I spent all day last week and changed the plugs which seemed to make it better but when it got hot it starts skipping/missing under light throttle when pulling away from standstill but still runs great if i drive it like i stole it.when the car is ticking over you can rev the car to the red line without a miss at all. Have got an Auto Xray code reader but is not showing a thing even the data that is shown when the car is running seems ok but then not to sure what i'm looking at. Forgot to mention that when i took it for it's yearly test the immissions guy said it was running rich which you could smell,
Sorry to waffle on so much hoping someone can help. many thanks. Richard

 

[Schrade]

Get all codes here, and post up.

 

[Mr Genn]

Have got a code reader and it is showing no codes. The car doesn't know there is anything wrong with it! Its quite a violent cough but only when under low throttle, seems a bit worse when it get warmer. If I drive it like I stole it there is no problem, except a speeding ticket! Richard

 

[Schrade]

No codes at all? When I say codes, I'm not meaning look for an SES light...

Get fuel pressure readings, static and dynamic, including pressure bleed-down times. Search my posts here for procedures, and post back.


edit: just noticed you do Auto X-ray...
Get FP readings, COMPLETE. See you tube for reference, but NOT for exact procedures nope...

 

[TWISTERUP]

Another possibility plug wires/coil wire.....just sayin'

 

[Mr Genn]

Should get a new set of leads by the weekend and hope to swop them over to see if that makes a difference. need to see if a mobile mechanic can come out to the car and check fuel pressure as it is a pain to drive in traffic. Richard

 

[bucket]

Hi all, sorry if this has been covered before but kind of getting desperate. I live in England which makes it hard for a garage to look at my car as they haven't realy got a clue. I have a '92 LTI all stock with 50,000 miles on the clock, i replaced the OPTI with a MSD one last year due to the car missing and making a pinking noise when under hard throttle, everything was great for about 6 weeks when the car started to miss fire under light throttle this time, if i give it a foot full on the gas i would end up leaving my tires on the road and probably getting a speeding ticket. so i kind of lost interested with the car it spent 8 months in the garage under cover till now.
I spent all day last week and changed the plugs which seemed to make it better but when it got hot it starts skipping/missing under light throttle when pulling away from standstill but still runs great if i drive it like i stole it.when the car is ticking over you can rev the car to the red line without a miss at all. Have got an Auto Xray code reader but is not showing a thing even the data that is shown when the car is running seems ok but then not to sure what i'm looking at. Forgot to mention that when i took it for it's yearly test the immissions guy said it was running rich which you could smell,
Sorry to waffle on so much hoping someone can help. many thanks. Richard

perhaps EGR valve.?
just guessing, of course..but that would also cause a ping on start up...im jus sayin...
howdy

 

[bucket]

Should get a new set of leads by the weekend and hope to swop them over to see if that makes a difference. need to see if a mobile mechanic can come out to the car and check fuel pressure as it is a pain to drive in traffic. Richard

im hip to traffic...lol
LA has a bit of that you know:cool

 

[Schrade]

Another poster just solved his 'low rpm misfire under load' problem in thread Why the miss? He said it was an EGR problem. http://www.corvetteactioncenter.com/forums/c4-technical-performance/115157-why-miss-5.html His is L98, not LT1. They're similar, but don't have too many problems in common, like vacuum/EGR problems.

Is your loping idle at all?

 

[bucket]

Another poster just solved his 'low rpm misfire under load' problem in thread Why the miss? He said it was an EGR problem. http://www.corvetteactioncenter.com/forums/c4-technical-performance/115157-why-miss-5.html His is L98, not LT1. They're similar, but don't have too many problems in common, like vacuum/EGR problems.

Is your loping idle at all?

good thinkin...lol

 

[Mr Genn]

No it idles fine, but i have noticed that when the car has been running for a while in the garage if i feather the thottle to about 1500 rpm and hold it there i can feel the the car missing but it goes away at 2000 rpm and if i rev hard from idle it will rev to the red line with no problems what so ever.
My leads turned up earlier today and i have now put them on along with the new plugs and still the same, had to switch off the car as it's nearly 10pm and pitch black and some curtains are twitching so don't want to upset the neigbors to much as they aren't the quietest car around. Many thanks for your suggestions. Richard

 

[roger longman]

Hi Mr Geen, I'm an English transplant, from Purley, now living in S. california. My problem was the one referred to by Schrade -Why the miss ?- I replaced everything before blocking off the EGR. My symptoms were almost the same as yours. Try it, it doesn't cost anything. How do you afford the petrol for it, over there? Roger.

 

[Mr Genn]

Hi Roger, its been off the road since December so I've been able to save up for it. Gas just went up to £104.9 a liter!!!! Rich

 

[Mr Genn]

Checked EGR valve, i ran the car till hot and opened it manualy and the car stubbled as it said it should in the book, so i assume that it is ok. Richard

 

[bucket]

Checked EGR valve, i ran the car till hot and opened it manualy and the car stubbled as it said it should in the book, so i assume that it is ok. Richard

maybe...that proves that it will open but does it close.??

 

[roger longman]

Checked EGR valve, i ran the car till hot and opened it manualy and the car stubbled as it said it should in the book, so i assume that it is ok. Richard

Hi Richard, No, what you should do is : pull off the hose from the intake and screw into it a small stud/bolt and then take it for a spin. Do the pumps show litres and gallons, or would a price per glns figure give recurring nightmares ? Roger.

 

[bucket]

hi richard, no, what you should do is : Pull off the hose from the intake and screw into it a small stud/bolt and then take it for a spin. Do the pumps show litres and gallons, or would a price per glns figure give recurring nightmares ? Roger.

$6.65 us

 

[Mr Genn]

Hi Richard, No, what you should do is : pull off the hose from the intake and screw into it a small stud/bolt and then take it for a spin. Do the pumps show litres and gallons, or would a price per glns figure give recurring nightmares ? Roger.

No the price is in litres on the pumps, it so the public can't see how much a gallon we are all paying, it seems to go up every day as you drive by the garge you end up saying another 1 pence (1.65 cents) a litre to find for gas.

 

[bucket]

No the price is in litres on the pumps, it so the public can't see how much a gallon we are all paying, it seems to go up every day as you drive by the garge you end up saying another 1 pence (1.65 cents) a litre to find for gas.

is your steering wheel on the left.??
jus curious if chevrolet ever made a british model vette...

 

[Mr Genn]

Yes its on the left, its totally standard with 50,000 miles on the clock and in superb condition - which it should be if its spending half its life in my garage!! Rich