Dead miss at idle

[OnTheRoadAgain]

I have a dead miss at idle; I replaced coil and spark plug (was fouled), no change. Dealer wanted ALL coils AND ALL injectors; 2 month wait for parts and $3,000, even though #6 was the dead cylinder. I understand no one wants to be responsible for every driveability issue once they pull a manifold for 1 or 2 injectors, but one cylinder is missfiring. ALL coils and injectors sounded extreme.

Experienced and well recommended Infinity Tech says it is probably bad fuel injector, coils are pretty reliable on this year car. I'm probably doing all injectors to play safe.

Since I'm (not me, the Tech) pulling manifold for 2nd time in a few months (hoses 1st time - different shop emergency), I'm worried what else?

what are symptoms of knock sensors? can they be replaced without pulling manifold if nec later?

car runs good except for miss at idle....

1991 Q45, 159,000 miles.Dealer (out of town now) serviced since new.

BTW this started as an intermittent problem then became permanent; tried a Lucas gas additive, then a BG treatment no change whatsoever.

Thanks

[96Qowner]

Unfortunately, the plastic body of the 90-93 injectors react with ethanol and swell, destroying the internal wiring.

zerothread?id=329342

zerothread?id=214756

zerothread?id=297405

As far as the knock sensors, you should probably plan to replace them and their harness when you pull the manifold - can't get at them otherwise. You can test them as well as the injectors with instructions from Q45.org.

http://www.q45.org/ohminjectors.html

I would be surprised if they're working correctly - don't usually last 159K miles.

[OnTheRoadAgain]

Thanks for the quick reply... I read everything about the gas additives.... not much I can do.... sound like too much engineering to change over to newer style injectors... I guess I have to decide on Knock sensors or not.

[maxnix]

Strong evidence that early single pintle injectors are killed by ethanol. So you may want to consider a conversion to later rotary valved injectors.

Do complete your profile so we know where you are and what you are driving in case you don't include it in your post.

[OnTheRoadAgain]

Strong evidence that early single pintle injectors are killed by ethanol. So you may want to consider a conversion to later rotary valved injectors.

Do complete your profile so we know where you are and what you are driving in case you don't include it in your post.

yes, I read that, but it means changing fuel rails, connectors or harness too? And there were some reports that modified fuels were run in some cars for 100k with no problems, and another report that some replacement injectors may have been modified to withstand the newer blends?

I JUST resigned to having to do ALL instead of a few, much less changing other equiptment. I suppose if I was doing it myself I might think differently, but my garage is crammed, and do not have access to a spare car right now, so any more downtime from making mods are too inconvenient.

I'm confused by one point, that the new blends mix water better with the gas, and another that said adding more water dispersant makes things even worse? Did I understand that correctly?

[maxnix]

First thing, you need to hook up with

Keith Vanmeter Auto Repair(856) 415-2022395 Wenonah AveMantua, NJ 08051

Secondly, just replacing the injectors with the old design may not solve the innate problem they have with ethanol, assuming you are in or soon to be in such an area.

Check the threads, http://www.deatschwerks.com and the eBay auctions, and see if you can get the later injectors in.

TexasOil has some posts about adapting the newer injectors to the old rails in IOM. This is all new territory for everyone with an early Q45.

[OnTheRoadAgain]

First thing, you need to hook up with

Keith Vanmeter Auto Repair(856) 415-2022395 Wenonah AveMantua, NJ 08051

Secondly, just replacing the injectors with the old design may not solve the innate problem they have with ethanol, assuming you are in or soon to be in such an area.

Check the threads, http://www.deatschwerks.com and the eBay auctions, and see if you can get the later injectors in.

TexasOil has some posts about adapting the newer injectors to the old rails in IOM. This is all new territory for everyone with an early Q45.

Yes, I met with Keith last week. He looked at the car and is going to check it further next week. He said he was certain it is an injector. He is sharp. Great guy.

How would I find out how much if any ethanol in our gas? I saw it on a decal once, and drove away. NJ was requiring some special fuels in the winter, and people were getting sick breathing the fumes while filling up, so I think it was discontinued this past winter?

BTW, you guys are great, with the quick replies, it helps a lot.

[maxnix]

Ethanol notice should be posted at the pump, but in Joisey, who knows?

[OnTheRoadAgain]

Yes, I saw it posted prominently at BP tonite: "May contain up to 10% ethanol"

I haven't noticed this at other stations, but I really wasn't looking for it. (in NJ)

[Q451990]

I agree that replacing the coils sounds extreme... they are pretty much bulletproof on the older Q45s. You or your tech should be able to ohm test the injectors to get an idea of which ones are bad. Check out the how-to at http://www.q45.org if you want to check them yourself. If you're replacing all of the injectors, see if Keith will let you bring your own parts... these appear to be OEM at less than half price. Not confirmed, but seem to be.

http://www.fiveomotorsports.com

Good luck and keep us posted!

Heath

[96Qowner]

.... sound like too much engineering to change over to newer style injectors...

If it was just any ol' tech, I'd tend to agree with you, but if Keith is doing your work, you should talk to him about doing the conversion. You can either swap rails and harness, or Deatschwerks has an adapter kit.

http://www.deatschwerks.com/ca...67_68

Keith can also call Keith Bowers, a very knowledgeable NICO member who has done the conversion. He can be reached through his website.

http://www.activesuspensionsys....html

It really shouldn't cost much more to convert to the newer injectors.

[maxnix]

Or you could edit and print a compendium of the posts here.

Be sure to separate facts from conjecture so Keith doesn't have to waste time unless he wants to.