Okay, try this one on for size. Here's the symptom...

(2.8L 164k)

Anything over 1/4 throttle and the car falls on its face. Flat. Has intake backfire. Throws no codes. Its okay if you granny it, but step on the gas and the car just limps.

What I've checked...

Timing (duh) - almost spot on. Though, when over 1/4 throttle, the timing goes from 16A to 0-20B (??? WTF)

Ignition module - just ducky

MAF - bought a new one.

Wires - those are brand new

Plugs - Autolite Platinums. still good lookin

Cap/rotor - look fine to me

ECM - swapped out, no change

Coil - swapped out, no change

Pickup coil - ohmed out like new (770k)

TPS - smooth increase in resistance

Water Temp sensor - ohms like new with temp

Fuel filter - brand new

Injector Duty % - seems fine

Fuel Pressure - spot on chap

And - It still does this when the car is in Spark Advance Disable (A-B on ALDL)

Since I've rebuilt this ENTIRE car in December, I've had no problems at all. This happened over night. The only thing that I can think of is the hydrolic lifters are sticking again. I've replaced them all before when the car was making this intake backfire (don't know what to call it). Just did the oil and filter 1k ago. Drivetrain has been taken good care of its entire life.

So I'm hoping for the "you idiot, check the ...", so if you have any idea, feel free! I've got a Camaro meet to go to on Sunday so I really want to figure this out.

-travis

 

Just a quick question here since you mention the timing jumping like it has. Have you looked at the roll pin that holds the distributor driveshaft in place. A friend had a similar problem like yours and the roll pin had snapped allowing the driveshaft to wander some.

 

Well...I just broke the rotor trying that out. So I assume that the pin in intact. Also, it doesn't jump around, the timing retards pretty smoothly. I'm going to replace the cap/rotor and then check for intake leaks. I hope I find something....

 

With the timing connector disconnected, base timing should advance at around 1800 rpm. This is the backup timing advance. If it doesn't advance or if it bounces around you need to rebuild the distributor.

Also, check for a plugged cat. Also, you symptoms indicate a lean condition....what fuel pressure are you getting at the rail key on engine off? Running?

 

Check your pickup coil again {Pickup coil - ohmed out like new (770k) }. Should be ca. 800 ohms, if at 770k then it is bad.

RBob.

 

Alright, my bad. The pickup coil reads 770 ohms. I just replaced the IGM and the car starts and runs. But it still retards the timing at greater than 1/4 throttle. It had been suggested that there is a lifter tick that the knock sensor is finding. If this is the case, would it retard the timing that much? I also have an exhaust leak at the manifold that I'm going to fix right now. I will also inspect all of the connections under the hood.

Remember, this problem is not present when the engine is cold, and it retards it more as the engine gets warmer (with cracked throttle). This is really frustrating. I'll pull all of the plugs while I'm at it and check those too.

Where is the knock sensor at? I can't seem to find it in the manual anywhere....

 

I'm sorry, I forgot to answer you question. No cat, and 42psi. Leaks down a little bit, about 2psi a minute or so.

 

Build a new 3.1l :rockon:

j/k bro. I have no clue as whats wrong

 

What if....the coils that I had were bad enough to short out the ignition control modules that I put in. Cuz when I put in a new one, it runs for a little bit, then it will do the same thing. Now its not starting at all....ARRGGG!!!

 

Well...I figured that I'd buy a new coil...what the hell. So I got the MSD coil in hopes of a hotter spark. No change. Then I traded out the IGM AGAIN! Then it wouldn't start! Rut ro Raggy... pulled the pickup coil lead out, hooked it up to my multi-meater and boy-oly, I've got an intermittent break in my pickup coil! Got my bro picking a new one up for me so we'll see if it fixes it...

 

Alright, seems like the pickup coil was the cause of my no spark situation! Woohoo! I haven't timed it yet, but it seemed to have fixed itself. Too bad I didn't replace the 15 dollar part before I spent 150.....

 

Now go home at lunch and time the damn thing

Then you can start putting on your new gfx and other parts

 

Oh hell ya! Plus I got the non-ac heater box now!

 

Alright guys. Bad pickup coil! Car on the road again! Thank you all for your help and suggestions!