Need injector help Q45

[Alan]

Hi Guys, I've been faithfully lurking the board, and now I need your help again.

Wifes 92 Q has a check engine light, and code 51. I have had 2 injectors replaced at the dealer, that is a 6 hour round trip. I think in the interest of convienience (not to mention $$), I should at least attempt to find the bad injector, if it is does not require plenum removal, I'll go for it. If it's under the plenum, I'll probably got to the dealer (or Wes? ;-0)

Do you pull the electrical connector off the injector, or pry?

This time the problem has been intermittent, appeared for a week, then gone for almost 2 months. Should I run some injector cleaner and drive it a little more?

Deadalus, I can't find your post on injector checking, but the manual seems fairly straightforward.

Can you guys dial me, or warn me off?

Thanks to all you frequent, and even infrequent posters. As much as we love our car, ownership would be most unpleasant without this forum and JT @ Scottsdale.

Cheers, Alan

[elwesso]

Well, FYI code 51 is injector circuit.. My guess is that the entire harness will need to be replaced, and not the injecotrs.... A bad injector would throw the injector leak code... Code 45

You pull off the electrical connector... mine were fused, so I used a little pressure with a pair of plyers to free the little thing you press to free ti.....

I dont think your injectors are to balme, rather I think its the harnes..... Maybe im wrong....

Id do ypur plenum AS LONG as i didnt have to do the KS. I dont want to do that again anytime soon, but I could do it in 1/2 the time I did last time.....

[Q451990]

I've never heard of a bad injector harness... I'd ohm test the injectors through the harness and see what you get.

Heath

[elwesso]

Thats what I get for not doing my homework and speculating!!

THe FSM says to check the injectors, nothing about the harness!! The easiest way would be to have the dealer do a power balance test (you said its there) and you could go from there.....

Id be interested to hear a good step by step instructional on how to ohm the injectors at the harness.....

[Alan]

I was not very clear in my initial post. In the past 2 years I have been to the dealer on separate occasions for injectors. This is a recent new problem, feels exactly like the other 2 injector failures, I'm pretty sure I have an injector that is allowing too much fuel.

Heath, Why do you suggest resistance test thru the harness as opposed to at the injector.

Thanks for your input, gents. Alan

[elwesso]

You have to take off the plenum to get to the injectors to test each one... Matter of undoing a connector to having to rip it all apart.....

What injectors have been replaced over the past 2 years.... Id replace the other ones and put a new harness on there for safe measure, only $20ish from Joe.....

[DAEDALUS]

Alan, you have email.

Checking through the harness is the best way, as it will check both the harness and the injector at the same time. If you get a bad reading, then you have to check that injector and that harness bundle separately. FYI, the only injectors I can't reach without removing the plenum are #5 and #6. The others I can reach, though #3 and #4 elicit a few 4-letter words. I have seen a Q with a bad harness...there was 20-40 ohms resistance through 2 of the connectors. The injectors themselves were fine.

Ohm testing won't help diagnose an injectors that is stuck open with crud or varnish.

[Q45tech]

Current testing will allow you to see on an oscilloscope the moment the pintle lifts off the seat, as a squiggle [~] in the 45 degree graph [current ramp up].

Power balance test is the 1st step.......then you narrow in on the problem.

[shadedoc]

How about di-electric greases on the connectors guys??

[elwesso]

Thats always a good idea, something i should have done while I was underplenum.....

[Alan]

With a ton of help from Robert (Deadalus) and posts by Wes and Qdog I'm in the process of replacing #4 and #7 injectors. I have r and r'd # 4, by loosening the plenum, and weasling around under it with a ratcheting offset screwdriver. I have been able to get the cap off #7 (more pushing on plenum) and I'm still trying to pull it out. I've been lubing it up with silicone spray, and a spray can of Liquid Wrench. Any tips on getting the injector out? I'm surprised by how hard these hoses are 'cause the dealer had the plenum off just 2 years ago, my impression was that the techs are first class, and we weren't trying to pinch pennies. I hope the underplenum hoses are more pliable as I am moving stuff around. Am I foolish not to pull the plenum off? The job is almost done and I am planning on a little more finessing( weasling), and no more disconnecting. Thanks, Alan

[Alan]

I'm back. I got #7 out. Yeah. The lower o ring stayed seated in it's groove. I am very tempted to leave it and just put a top o ring on the new injector. I can get down inside with dental pcicks, but I am thinking with some nice silicone paste lube it might be better to leave it, rather than risk a nick to the groove, and/or drop pieces of O ring inside. Hoping for some definative answers form those that are in the know, and you know who you are. Thanks a million, Alan

[DAEDALUS]

I highly recommend replacing it. It's simply too risky to attempt to reuse seals. If there's really any risk of it coming apart in pieces, then it definitely has to be replaced.

[Q451990]

No doubt... replace it! A leak with a lower o-ring can flood that cylinder and cause hydrolocking. There's a bent piston arm at T3 hanging on the wall as a reminder - a screw up several years ago by a tech who's no longer there.

Heath

[Alan]

Thanks guys!!! I'm all done and everything went real smooth. Probably have 6 hours total. No way could I have even thought to do this without all the info available here.

All the best, Alan

[DAEDALUS]

Good to hear Alan, glad to help!