Solders18

My adventure started on tuesday when i was driving to school. it started running rough and progressively got worse as i kept driving. by the time i got to school and parked (about 5 minutes/1.5 miles) it felt like it was running on 7 cylinders. i thought it could have been a burnt spark wire so i checked them right then and nothing, they were all well clear of the manifold. After class i started it up and was heading out of town and was running just fine. i hit the bridge to go over the river (about 5 minutes/1.5 miles) it started acting up again. Considering it was 12 miles to the other campus i immediately headed back home. I checked wires again and more thoroughly, but still clean. I checked connections on the wires both at the dizzy and the plugs, all were good. I checked, cap and rotor, pickup points, coil, plugs, and wires. I ended up replacing the distributor because i thought it was pickup points (came with ignition module). Still runs like poo. when first fired up it will run just about perfect then will get progressively poopier. I threw the stock chip back in it thinking my burnt chip went bad and it took longer for it to turn poopy but ended in the same result. Driving it would start good and get worse by missing under load then going to missing under any load(holding 50 mph was hard)

As it is right now, i have reset the timing and it initially starts and runs good, then as it idles down it will miss pretty hard and just rough generally rough. It will die within a second or two of putting it in gear and haven't been able to take it for a test drive. I verified that the rotor was pointing at the #1 spark plug at TDC. I have a datalog of when i had it out earlier if anyone is interested.

I have tested/replaced:
Fuel pressure (42 KOEO/32-34 running with vac)
Coil (known working from another motor)
Pickup points (tested and now new)
Wires (new a month ago)
spark plugs (new a month ago)
injectors (south bay bosch III's in december)
Compression (160-150-150-150-155-145-150-150-150)
fuel filter (new)
Distributor (new)
Ignition module (new)
O2 sensor

I might have forgotten something, its been a long three days...

Thank you for reading my rather long winded post, i wanted to give as much information as possible. The car is an 87 iroc 5.7 tpi 700r4

ploegi

Disconnect the O2 sensor, and see if the problem goes away.

Solders18

Thank you for the reply, i will try that when i get back from class.

If it fixes it does it mean the O2 sensor is bad? I did replace it with another O2 i had.

Solders18

disconnected the O2 and no change. I just ohmed all the spark plug wires and the injectors and they all checked out. Are there any ideas? Things to check? i am out of ideas

ploegi

See what fuel pressure is doing.

Yeah, you just tested to see if the O2 was bad.

Solders18

I tested fuel pressure yesterday. 42 psi with Key on engine off. 32-35 running at idle with the vacuum reference hooked up. pressure rose with throttle input up to around 45. i believe it was 45 without the vacuum hooked up. with as tight as i could clamp the return line (don't have vise grips) pressure got to 70

Edit: i found a portable vise that i could clamp the return line good and tight. still only reached 70 but i saw it was bleeding down pretty quick.

ploegi

Next comes a fun one..... is the EGR valve sticking open? Solenoid bad? (disconnect vacuum from solenoid, see if things smooth out.)

Getting any black smoke while idling?

Solders18

i haven't had EGR hooked up in.... 4 or 5 years. Any way it could magically open itself?

ploegi

Not that I am aware of...... (I have tried waving my magic wand REALLY hard, and it just didn't make any difference at all..... bummer. )

Got a spare ignition module to toss into the dist?

Solders18

The ignition module is the first thing i replaced. got a new Echilin one from napa and threw that in there, no change. and I have the new one that came on the dizzy on tuesday in there now. I returned the one from napa (shhh! don't tell them i installed it) so i just have the original one that was on it when the problems started.

ploegi

It sounds like something is getting hot, and failing.... but, you have been thru all the usual suspects..... if you have a MAF sensor, let the engine idle, and whack the maf with a screwdriver handle. See if the engine stumbles.... either that, or disconnect it, and go for a ride.....

Solders18

I disconnected the MAF but didn't even put it in gear because it was running so bad.

ploegi

Pull some plugs. See what they look like.

For my next WAG, temp sensor?

Solders18

Plugs pulled on wednesday. they all look more or less the same. Tunerpro shows temp correctly. 185 when warmed up.

Solders18

Here's a log export of when i had it out yesterday.

Terrible short.xls

ploegi

At what point in the log was it screwing up?

Solders18

The fueling is running pig rich. Had blm's right around 128. I had a wiped cam lobe suggested to me so I will test that when I get home

ploegi

Have a look in the log at line 2904-5... Things freak out at that point. Battery voltage goes to zero, engine RPM goes to zero, IAC cranks itself wide open, etc..... wonder why....

Solders18

2904= Engine turned off, keys thrown on the counter, and a Pepsi taken out of the fridge

ploegi

That explains a lot.

Solders18

Well its not the cam... i am pretty sure it is either spark or injectors

southbay08

it's unusual for the bosch lll's to have problems unless there is some debris in the injector. We have never seen one with a bad coil. If you want, send them in and we'll be more than happy to test them for you. Let us know.

Solders18

I will pull them out today and see if I can find any obvious restrictions and let you know. Thanks for the reply!

Solders18

Well after taking the plenum and fuel rail off and visually inspecting and ohm-ing each injector, I now have a couple new symptoms. Turning the key on I can hear the fuel pump priming but I walk around the front I barely get any pressure out of the fuel port. I tested the car before I took it apart and it started and ran just fine but with the usual miss. It is now starting very hard and running around 2000 rpm then promptly dying. I managed to catch it and throttle it by hand and it sounded baaaaad; It didn't want to run. I thought of air in the fuel rail but it should clear out in the return line after the first, maybe second prime correct?

Solders18

The engine is clearly struggling to turn over one piston when starting so in my continuing suspicion of a leaky injector, i pulled the fuse to the fuel pump to prevent priming and tried starting the car. The first time it clearly stressed over the one cylinder, fired once in each cylinder, and immediately died. the second time, figuring leftover pressure and fuel were gone, i tried starting it again and it turned over how it should nice and easy.

rusty vango

i would do a compression test on it. the first thing to do here is make sure the basic health of the mechanical parts are up to the task.THEN work on the fueling and computer bits.otherwise you may end up throwing $100s at it on the off hand chance something will reveal itself.

Solders18

Look at original post

Solders18

Ended up being a leaky/failed... injector. I got and installed the old injectors today and it runs perfect again!!! thank you everyone for your help and input!