alright gents, (and ladies) having some issues. Here we go... When i first start the car up, it has the most eratic idle, which is most likely a broken vacuum line somewhere in the system, no clue as to where, but i might go ahead and start looking, waaaaaaaaay to many wires and tubes under the hood of these cars in my personal opinion. Past that, when i started it today, the engine turned over, and died (didn't like die out slowly, just died out), started it again, and it did the same thing, started it again, gave the car some gas to keep it from dying, and it maintained at 1000-2000 RPM with my foot on the gas, removed my foot slowly, dropped to 500 then died again. So, i stopped, waited a little bit, and the started the car again, and things worked out just fine. rough idle as normal, but fine. As i'm driving down the street with the car after this, i rolled to a stop (at a sign). Then as I hit the gas again, i heard a pop sound from the passenger side of the car, (i've heard it around 3 times now) sounds almost like a backfire, but not quite as loud. I drive around for a while, stop at my work, and at the airport (about 5-10 minutes away) the car heats up properly and whatnot, and there's no more pop. The idle smooths out alot once it's in closed loop , etc. But, what's the popping noise from earlier? Another issue, after i popped the hood up, i listened to the motor. Could hear a tap tap tap, from under the intake plenum, most likely it's injector knock (motor's a new jasper engine...about 30k on the block now). What else should i start checking on right now? i'm going to be driving the car from my university back home this weekend, 2.5hrs, shouldn't be to bad, and i've got the cell incase i've got some issues on the way in. But i'd like to have an idea of what i should be looking at, and if i should pull some injectors from a bone yard while i'm home, and have them sent to cruizinperformance.com any help will be appreciated all...and thanx in advance.

 

Don't know about the injector "knock"; injectors are supposed to make a ticking noise, but I haven't heard of a knocking noise. Could it be detonation from over-advanced timing?

But your symptoms sound like what I'm having. I diagnosed the car as having a leaking injector a few months ago:

I thought I could find the leaker with a multimeter, but the guys at the tech board say it can't be done. I've got a set of injectors I've gotta send to Rich... one of these days. I just hope my cold start injector (85-89 2.8's) isn't the leaker... I'll wind up swapping in all the injectors, and will still have a problem. Only way to check for the leaker is to pull the rail and pressurize the system- and you know that at that point, might as well swap a clean set of injectors in!!

They also reminded me about reading the plugs... said to prime the system a few times without starting the car and look for a spark plug tip that was wet with fuel.

 

good point tom....

The noise actually is more of a ticking noise than a knock....i thought i had remebered once before you saying something about a leaky injector would make that ticking / knocking sound. Neway. through all my engine theory classes, etc. Ive never actually gotten to hear the sound of a detonating engine, which isn't very cool. Have seen it done in a glass cylinder before, and konw what makes it happen, but, never heard of it. Last time i went to check the timing i couldn't exactly do it right because i couldn't find the EST to disconnect it, when i checked the timing with the EST plugged in, the computer was really compensating for something, had timing advanced to like 23 degrees.

 

Yeah, the computer really flips the timing off the scale with the EST plugged in. Look for that connector in the wire loom that runs along the top of your heater/condensor box... I had a hell of a time finding it on my car. And then on my friend's car that I did the engine swap on, I coudln't find it at ALL, even after hunting thru that wire loom! But his car had a butcher job done to the wiring harness in other places, so the previous owner must've eliminated it somehow.

Wait, I think Vader's posted a pic to show it's location, let me do a search... ah , here we go, got pics by both Dale and then Vader. Check it out: https://www.thirdgen.org/techbb2/sho...threadid=32250 Looks like Xenodrgn was helping out again on that post, too...

Oh yeah and as for the detonation, it'll sound like pinging, but it'll be an intense ping. That's the worst I've heard it (from my car, when it destroyed the #1 spark plug). What did it do to the glass? How'd they show that, anyway? Put a spark plug inside?

 

thanx tom, I'm going to go look at the EST and see if i can find the damn thing in a little bit...before i go for a lil' flight back home for some good white castles (if anyone knows that those are). Oh, and the video was really bad, and really old, think it was put out by GM though, and yes, it was a sparkplug put intop of a glass cylinder (think it was a thick glass...but who knows). either way, you could see the two fire fronts collide to make the pinging noise, and yes i've got pinging....will have to take a peak at the plugs when i feel motivated enough to pull them.