Poor idle, "missing", Old & new injectors

[rlibraman2k]

I have a 94 Q and it was running but had an intermittent bucking and jerking so I had someone take my injectors out to clean then. After doing this, he put the injectors back in and it constantly had a bad idle especially in drive or reverse. Then, I bought injectors off of Ebay and put the whole injectors and new rail in and it it STILL doing the same thing. The injectors are ohming @ 12.5 so doesnt sound right that these injectors would cause the SAME problem--Help please!!--If he dropped a small piece of rubber glove and 1 of the plastic fuel rail washers in 1 of the intakes, could this cause the above problem? PLEASE HELP!!

[Q45tech]

What is the exact idle rpm, what is the dry, wet static compression of each cylinder, what is the running compression, what is the power balance rpm deviation?

How old are OEM spark plugs miles and hours of use?What is fuel pressure?

Things one checks to diagnose idle problems!

[Peterofdevon]

Also, clean the MAS and make sure the connectors have not oxidized. Your symptons point this way.

Peter

[Q451990]

Dropping stuff in there isn't a great idea...

In all of my injector failures, the bad injector has fouled the corresponding spark plug. So even after the injector replacement - the miss was still there. I had to pull and clean the plug to get it right...

Heath

[rlibraman2k]

I thank u for your help--gonna try changing the plugs tomrrow--will keep u guys updated--

[Q45tech]

USE BG44k and exercise the HELL out of engine for hours to blow out all the carbon and deposits on valves.

[lino]

Also, clean the MAS and make sure the connectors have not oxidized. Your symptons point this way.

Peter

What's the best way to deal with a connector that's oxidized?

[ToddRamsey]

I am also having some issues with my 1990 Infiniti Q45 with idling. My check engine light was on, and I brought it into my mechanic. The computer was registered a leaky fuel injector, and crank angle signal sensor was bad. I replaced them, for a hefty fee. Then the problem got better for about an hour, and it started up again. I went back to the mechanics, and he realized my alternator was out of wack. It was pumping 150amps at idle, when it was supposed to be pumping 90amps. AND, it was cranking out 6amps of AC power. So he figured this was the problem, and replaced it, also for a hefty fee. Upon driving it home, the problem came back. What happens is I will feel my power lessen as I drive, and when I slow down under 10mph the RPM gauge starts surging up and down. I parked my car and watched my RPM gauge jump up to 1200RPM, then drop down to about 150/200rpm(almost dying), then jump back up, and back down. After this continued for about a minute, the engine revved up real well, up to about 1500RPM and held it there (similar to when you start the car), then it dropped down to its regular idle RPM (about 700rpm) and worked fine. The next day, the car worked fine, until I was parking it at work. The RPMs again starting jumping around, I watched for a moment, and decided to tap the gas very lightly. All of the sudden the idle was completely stable, and after about 5 seconds my check engine light came back on.

So now my car is back at the mechanics, and we're hoping that the computers diagnostic will help us identify the problem. I will keep you guys informed on how my situation turns out.

PS; I have all new spark plugs, and had a oil flush, fuel line/injector flush, and transmission flush a month or so before these problems started to occur.

[goody90q45]

I am also having some issues with my 1990 Infiniti Q45 with idling. My check engine light was on, and I brought it into my mechanic. The computer was registered a leaky fuel injector, and crank angle signal sensor was bad. I replaced them, for a hefty fee.

California Code 45 usually doesn't really mean leaking injectors just running rich or sluggish weak O2..............the ecu cannot correct by leaning bank so it throw a code saying beyond 20% error.

I had a 90Q with the same ECU code. It was the O2 sensors, not leaky injectors. I hope your mechanic didn't have you change out all 8, at least without ohming them first. Your other issue is a bad MAF, a bad or loose MAF connector, or both. No thread jacking. Check your e-mail.

[ponzy]

I am also having some issues with my 1990 Infiniti Q45 with idling. My check engine light was on, and I brought it into my mechanic. The computer was registered a leaky fuel injector, and crank angle signal sensor was bad. I replaced them, for a hefty fee. Then the problem got better for about an hour, and it started up again. I went back to the mechanics, and he realized my alternator was out of wack. It was pumping 150amps at idle, when it was supposed to be pumping 90amps. AND, it was cranking out 6amps of AC power. So he figured this was the problem, and replaced it, also for a hefty fee. Upon driving it home, the problem came back. What happens is I will feel my power lessen as I drive, and when I slow down under 10mph the RPM gauge starts surging up and down. I parked my car and watched my RPM gauge jump up to 1200RPM, then drop down to about 150/200rpm(almost dying), then jump back up, and back down. After this continued for about a minute, the engine revved up real well, up to about 1500RPM and held it there (similar to when you start the car), then it dropped down to its regular idle RPM (about 700rpm) and worked fine. The next day, the car worked fine, until I was parking it at work. The RPMs again starting jumping around, I watched for a moment, and decided to tap the gas very lightly. All of the sudden the idle was completely stable, and after about 5 seconds my check engine light came back on.

So now my car is back at the mechanics, and we're hoping that the computers diagnostic will help us identify the problem. I will keep you guys informed on how my situation turns out.

PS; I have all new spark plugs, and had a oil flush, fuel line/injector flush, and transmission flush a month or so before these problems started to occur.

could these be signs of vaccum hose leak?

[goody90q45]

Could these be signs of vaccum hose leak?

Could be a vac hose leak but it's usually best to start with the easy stuff. Clean the MAF connector and ohm the injectors and KS= 30 minutes. Chase a vac hose leak= hours.

[maxnix]

Todd, welcome to NICO.

I suggest you retire the generic mechanic you are using and get your car to http://www.jerrytucker.net

More money is wasted and damage done by mechanics unfamiliar with this car. If he doesn't have a Consult, that seals the deal.

[ToddRamsey]

Hell yeah, you guys are awesome. Thanks for all the quick responses. I called my mechanic after receiving the 045 error code (leaky fuel injector) again. He had been checking out the fuel injectors all day without finding any problems. I called him up and told him what I read here, and he became very excited. He is now going to check out the MAF, look for a vacuum hose leak, and check the o2 sensor. He said the tech support team he was calling had no knowledge like this, and he's very glad that I found this out. I hope that you guys are correct, and my Q45 will be back in action shortly. I'll keep you all posted.

[1990Q45'r]

Having a injector rail washer in the intake tube can cause idle problems. I would get it out ASAP!

[silkysmoothyjud]

Food for thought. Just got my ghetto used injectors that I bought off ebay back from deatchworks and I am experiencing "miss fire" and they ohm out very well. hmmmmmmmmmmmmmmmmm buy freakin new ones dude!!!
Modified by silkysmoothyjud at 9:51 PM 5/23/2007

[maxnix]

Food for thoughtJ. Just got my ghetto used injectors that I bought off ebay back from deatchworks and I am experiencing "miss fire" and they ohm out very well. hmmmmmmmmmmmmmmmmm buy freakin new ones dude!!!

What we always say, but some think they can save money by spending less on questionable used wear items.

Thanks for your testimony.
Modified by maxnix at 8:44 PM 5/30/2007

[silkysmoothyjud]

My pleasure. The fact that they ohmed out scared me a little. I never would have found it unless I did it myself. Unless there is another way one can tell an injector is bad. Is there another way? Said injectors "clicked" louder than the rest. Almost as loud as snapping a finger. I will get my new ones next week and report when I am done. Peace.

[silkysmoothyjud]

I put the new one in today and I will NEVER try and cheap out on this car again.....

[maxnix]

Good job. Staying on top of maitenance when one can have confidence in the components one replaces.

[3Q Jay]

My pleasure. The fact that they ohmed out scared me a little. I never would have found it unless I did it myself. Unless there is another way one can tell an injector is bad. Is there another way? Said injectors "clicked" louder than the rest. Almost as loud as snapping a finger. I will get my new ones next week and report when I am done. Peace.

thing is, ohming injectors is a crude indicator. yes, they must pass the static test of 11-12 ohm on the meter, but what you can't tell with your fluke meter is what the dynamic response of the injector is, even if it passes the static test. rise and fall times of the solenoid valve, under a variety of duty cycles. having an inductive probe with an storage oscilliscope on the injector harness is the only way to *really* know if the injector is good.since i don't have such elegant equipment, i just replace with oem new when they fail the static test.