The Camaro Club (UK)

I have a really annoying misfire on my 3.4 v6 4th gen
It was running all good but started to get a little lumpy so in went some new plugs and leads. Strange thing is now when I run it on petrol it is more pronounced and really bad between 1300 and 2100 rpm but it seems to go away after that. If I run it on lpg the misfire is still in the Same rev range but not as obvious.
Im actually really worried it might be a valve problem. But iit's only done 64k and had the lpg kit has only been on 18 months.

Anyone had this before on theirs?

May be buy a cheap code reader.

Coil would be where I'd start looking.

have a look for sparks under the hood at night when its dark.

I do have an obd2 Bluetooth reader that works with most cars but doesn't seem to with my camaro. What software would you recommend?
The software iv got works with most cars after 2000.
Funnily enough I used it Sunday for a 150 mile round trip and it was ok apart from hunting slightly when I stopped at lights once it had warmed up. But didn't do it all the time.
I'm starting to suspect egr valve or idle speed control valve maybe

Has it got an Opti spark ?

See this thread...
http://www.classiccamaroclubuk.com/phpB ... 704#p24704

Nope mines got the coil packs mounted on the right side of the engine as you stand looking under the hood

Sorry don't no anything about soft ware pack's which is why my wife banned me from buying anything newer than 1980

Still think coil but the next time it's playing up disconnect the MAT sensor and try it down the road.

Did you use the exact same type plugs that you removed? Gapped them? LPG Will have a different octane rating to petrol so would require a stronger or weaker spark making a problem more obvious on one fuel type than the other, if it's not the plugs then like pa said it'll be coil pack trouble I recon, long before the days of diagnostics we would remove the plugs and compare them to find out which cylinder the problem was with, if you have multiple coil packs you don't want to replace them all , when I were a nipper this was what we use to diagnose which cylinder had issues and every Haynes workshop manual had photos of spark plugs so you could read them

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1997 30th Anniversary SS SLP
1993 GMC Typhoon

i did use differnt plugs to what was fitted. but i used the ones that are recommended for the car some NGK something or others. but i also took out a set of NGK plugs and i noticed that the part number was just 1 number different to the ones that were already in.
i thought maybe that was the problem as when i first fitted them the misfire went and it was much better on petrol and gas.
it seems a really intermittent problem at the minute.
as i say i took it on a 160 ish mile round trip on sunday and it never coughed hardly apart from hunting a little when standing between about 500 and 1200 RPM which settled down after about 10 seconds.

maybe i should be looking at the idle control valve more and the EGR valve as unfortunately it probably shares a lot of bits like that in common with vauxhalls of a similar age which i know are prone for idling problems

Hmmm.... I'm LPG qualified but not on cars unfortunately , I also used to own a nitrous company and due to the extra heat created we always used to advise fitting spark plugs that were one stage colder , do you still have the plugs you removed? Could you clean them up and refit them to eliminate that as the problem? Maybe contact a company that does gas conversions and ask if the reccomend changing the plug type when gas is fitted? I'm just trying to think of all the cheap and obvious causes you could eliminate before spending out on other parts, are the leads you fitted exactly the same? Maybe they have a different core or something ?

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1997 30th Anniversary SS SLP
1993 GMC Typhoon

Yeah I do still have the old plugs. I did wonder about refitting them actually just to see what happens.
The plug leeds are just regular OEM ones I got from an American parts place (not sure of the name....cm frost I think)

As for an lpg place there's only 1 near me and I called in to ask and they wernt very helpfull just said book it in we charge 60 quid plus vat for a service and we will have a look at it
But most of their business I noticed is from things like big fast German stuff so I imagine they're not exactly American enthusiasts :/

I'm quite up on cars myself iv always done all my own work including engine rebuilds and general maintenance... But lpg is something I don't know much about having never delt with it before.
It's also been about 14 years since iv owned a petrol car myself lol