Replaced injector, now runs rough after warm up

[carl_in_florida]

I have a 91 240sx. I had a bad injector and replaced it. Car runs great . . .until it warms up. Then it spits and sputters.

any ideas? I did the ecu code thing and it came back 55.

I did not see any rotted or loose tubes. Though I don't exactly know which ones to check.

Tahnks for any help

[srpowered240sx]

pull the injector/s again to check the orings. did you use new ones, or re-use what was there? lube them up on the install?

[carl_in_florida]

I am guessing the new one had new orings. but I did a swap with another cylindar to make sure it was the injector. Maybe the other one was old? I don't know.

Will that cause it?

[srpowered240sx]

I am guessing the new one had new orings. but I did a swap with another cylindar to make sure it was the injector. Maybe the other one was old? I don't know.

Will that cause it?

yeah, it will definately cause a screwy idle with an injector leak. pull them at check the orings, then lube with a bit of wd40 and put them back in.

[Vegascorbin]

my 2 centsVaseline worked better for me than WD40 or Brake Clean (parts store recomended that one)

[grecco28]

check the inyectors resistance in cold first and then when starts the failurecheck it again...

range is 12- 15 ohms...

[silkysmoothyjud]

You did not buy new ones, did ya? No need to answer, I did the same thing, thought I was real smart saving all that cash until I bought brand new ones, and that rough idle went away. Bad coil in the injector, but it will still ohm out ok....Anybody wanna bet me?

[del82]

You did not buy new ones, did ya? No need to answer, I did the same thing, thought I was real smart saving all that cash until I bought brand new ones, and that rough idle went away. Bad coil in the injector, but it will still ohm out ok....Anybody wanna bet me?

I'll take that bet. If it doesn't run bad till closed loop, its not the injector he replaced. At that point he's running the full gambit of MAF to ECU problems, almost any sensor in the intake or exhaust system. You'll wanna have that sent to a tech for a proper diagnosis.

I suppose some quick things to do are to make sure you ran all your wires correctly on reassembly, and nothing's unplugged, then check your timing, and anything else you had to move around to replace that injector, even if it seems mundane.

[silkysmoothyjud]

IF the injector he replaced is used then I will take that bet. Been there done that, especially if it only happens if its warmed up. The only probs on a Q45 or the injectors or maf. Fuel pump will hum before failure. Please dont send this guy on a wild goose chase, just because it is very tempting to waste time on easier, less expensive things.....so, I refuse to rebut this thread again until we find out. WAS THAT INJECTOR USED/REFURBED, OR NEW. Like I said....it was not new OEM....do I have a wager?

[silkysmoothyjud]

ps, I had d-works clean two used injectors I bought off ebay, ran the tests, cleaned the injectors, checked out and ohmed out ok. REMOVED THE F'IN PLENUM, PUT THEM IN THERE (#s 3 and 4), ONLY TO HAVE TO ORDER NEW INJECTORS FROM JOE AND DO IT ALL OVER A FREAKIN AGAIN BECAUSE OF VIBRATIONS IN IDLE AFTER WARM. Now its back, vibration after warm, dammit!! Failing injectors is a common prob in a Q. Now Im done, went straight to Joe, ordered 4 more brand new OEM (done trying to skimp) so I dont have to remove my plenum again for a while. (523$) so 3-8 are brand new, injectors 1 and 2 can be replaced without removing the plenum.... ooook, now I have vented

[carl_in_florida]

I really appreciate the interest of late. I bought it remanufactured.

The problem is not as bad as it was but it still happens. I have been hesitant to buy a new one because money is tight. Thanks for the help.

I am willing to do whatever to try to fix this.

I had a bad injector replaced at the shop a few months ago and it feels the same when it happens. But it does not happen till the car gets warm and now it does not happen every time it gets warm.

[silkysmoothyjud]

buy a new one mine are 160 BUCKS APIECE brand new, 50 bucks refurb...tempting, isnt it, not anymore, just dropped phat cash on new ones. I dont want to have to do this again for a while......and I most certainly dont want to have to do it again, AFTER I JUST DID IT!!!!

[silkysmoothyjud]

also, you might have to replace more than one injector, you should replace in pairs, or just adjust your idle to fix your symptoms, unless it feels like your riding a mechanical bull after its warm. then the injector is totally shot...

[silkysmoothyjud]

Also, check your belts, a tight and /or loose belt may cause a "misfire" like vibration.....Just fixed my vibration. It was random, but it went away after I drove for a while. The vibration will be felt in your wheel and it will sometimes feel like it is comming from the rear rotors.....

[Habitjr21]

Will a 91 240sx start with a bad injector?

[silkysmoothyjud]

they were fuel injected? With one bad injector it should....

[Cone Junky]

Symptoms also sound like an intake leak. The car runs richer when cold and then leans out when warm. If you have an intake leak it will run way too lean once it warms up. The best way to check for leaks is a smoke test. If a smoke machine is not available you can use propane or carb cleaner to pinpoint a leak.This test costs nothing and should only take a few moments.

BTW- white lithium grease on the injector seals is the best way to install. Whit lithium is a moly grease so it doesn't have petroleum that will eat the rubber seals.

WD-40 is too thin and brake clean is just a cleaner, so it dries out the seals more than it lubes them.

[carl_in_florida]

I got starter fluid. anything in particular I should be spraying?

When I first start the car is fine. When it warms up, does not take long in Florida, the car spits and sputters. If I press the gas more than an inch or two while driving it chokes. If i hit the gas while in neutral a white smoke comes out and it smells like it it burning really rich. I am not going through oil so I don't think it is a ring or anything.

[Cone Junky]

If you have smoke, part throttle issues, and the smell of unburnt fuel I would lean more towards the MAF.

Spray the intake manifold were it meets the head and then all around the throttle body and around any vacuum hoses. If you don't get a jump in idle while spraying components it is more likely an electrical component failure. Try unplugging the coolant temp sensor too. If it is shorted the ECU will think it's freezing cold and run it rich.

[silkysmoothyjud]

Fuel pressure regulator bad perhaps? Check those fuel lines under direct sunlight, its easier to catch the mist. I wouldnt F with a gas smell...