1994 Q45 Running Rough

[Jmanolinsky]

My 1994 Q45a has 210K miles on it. A couple of months ago it started running really rough. It appeared to be running on less than all cylinders at all RPMs. It was so rough that when idling the car would shake. It would run rough at times and then run fine sometimes. It then began to run rough all the time. Just as I was about to dive under the hood to get to the bottom of the problem, it started to run great again. It did so for over two weeks, but now it is back to running rough again. My first thought when the problem appeared was injector trouble, but now I'm not so sure. Where would you begin to look for the problem?

Thanks,
Jman

PS: It does not feel like the MAF sensor connection where the car dies at idle. I am familiar with that problem.

[kevindanielk]

Omn test your injectors. If any of them gives you a 0 ohm reading, then it's not functional or spraying fuel. Last time my Q started shaking badly, one of the injectors got clogged and read 0 ohms when I tested it. It's a start.

[Jmanolinsky]

I checked the ones I could easily reach. Out of the six that I checked, four were around 13 ohms, one was over 200 ohms and one was 0 ohms. I got the connector off of number 7, but couldn't get the multi-meter probes on it at the same time to get a reading. Is there any way to check number 5 without removing the plenum? It seems buried. My car does have TCS. Where should I look for replacement injectors? The injectors seemed very brittle. Should I just replace them all?

[goody90q45]

.....Is there any way to check number 5 without removing the plenum? It seems buried........

Which 2 were reading high? You may be in luck if they're #1, #2 or #8.

You can ohm test all of the injectors through the connector on the passenger end of the plenum. Positive probe of the voltmeter to the positive post of the battery. Negative probe to each of the 8 pins. Opposite for the KS readings.



Yesterday I was going to suggest a bottle of Redline S1 fuel system cleaner in a 1/2 tank of gas thinking you had plugged injectors but with 2 of them ohming high it probably wouldn't help much.

[Jmanolinsky]

Hey Mike,
If I recall correctly, it was 4 that was dead and either 1 or 2 that was high. I wrote it down, but the paper is at home right now. Are 1, 2 and 8 the only injectors that can be replaced without plenum removal?

Thanks,
Jman

[goody90q45]

You can get to a couple of others by grinding the plenum or finding a small person with really strong hands (proctologist, dental hygeinist?) but #1, #2 and #8 are easy to get to. Do a search- Injector 4, injector 6, etc. I know there's been at least a few writeups on FI replacement without removing the plenum.

[Jmanolinsky]

How long would it take to remove the plenum and take out the injectors on a junk car that you weren't concerned about reassembling? Fuel rails? Thanks for the help!

[Jmanolinsky]

I went to pull-a-part today. I tried to get some used injectors. How the heck do you remove these things from the fuel rail without destroying them? I can't imagine trying to get mine out of my car. There are 2 other Q45s there with at least 1 bank of injectors still intact. I would like to replace 1,4 and 8. I thought maybe move my 2 over to number 1 and install the new/used ones all on the same side. Any words of wisdom, links to articles or other posts is greatly appreciated.

Jman

[goody90q45]

I went to pull-a-part today. I tried to get some used injectors. How the heck do you remove these things from the fuel rail without destroying them?.....

Spray the upper o-ring area with lube and start rotating the FI by hand until it turns freely. Once you can rotate it make a noose out of 3/16" diameter rope, cinch it around the plastic head, and apply steady upward pressure. After a few seconds you'll feel movement and it will pop out. Be ready to catch it.

If you're moving injectors around put the questionable ones in the 1, 2, and 8 ports in the fuel rail so you can get to them later without removing the plenum. The FI you trust go into the other ports. Make sure to clean any corrosion on the FI pins and lube them with dielectric grease.

[Jmanolinsky]

The four plastic fingers at the bottom of the injectors I tried to get yesterday broke if barely touched. I assume that this makes them worthless? They ohmed right at about 12 which I took to mean that they were a good find. I searched here for "injector 4" as you suggested, but didn't find anything. I would sure like to leave the plenum intacted if at all possible. I'm not wanting to open that can of worms if I can avoid it.

[goody90q45]

The pintle cap can be replaced but I'm not sure where to source them. I got a set from Deatschwerks but I heard they weren't selling them any more. Call them direct and see if they can help. You'll probably find the same on most FI you pull from any engine so get a set of 8. To install boil the cap in hot water for a few minutes to make it more pliable. It will pop right on. If that's all that's wrong with the injector and they ohm well you've got what you need. If any part of the plastic is cracked or missing I wouldn't use it. Go get more. If you have a choice get FI with other than a tan top since they would be replacements and newer.

One problem with salvage yard injectors is you don't know how long they've been there. My experience is the FI get gummed up with inactivity and even though they ohm well they could be plugged. Try whichever one is going into the #4 port in the 1 or 2 port for a few days first before you pull the plenum and put a plugged injector there.

[Jmanolinsky]

Thanks for the help. I really appreciate it.

All of the injectors that I saw yesterday were tan.

Pull-a-Part doesn't keep their cars too long so unless the car sat for a long time before they got it, it shouldn't be too bad. Is there some way to clean them before installing such as soaking in denatured alcohol or something?

[goody90q45]

You need to be able to flow the cleaner through the injector which would involve getting it to open and close. Unless you have an injector cleaning machine the best way would be to put them into #1 and #2 port and go through a 1/2 tank of gas with Redline injector cleaner, or send them to Deatchworks for their sonic cleaning.