chugga chugga

iac high counts are not going to give you back fires,.

stop ;ooking at the data for an answer,. DATA helps you tune an engine,. cel's tell when something is broke or nfg,.

something is hooked up wrong,.


Lets have a re-cap in chronological order of what you have done,..(to the poor engine_{

I get it Nick, weird running car is spitting out weird data. I just thought it was interesting.

I did some due diligence tonight, I validated that the spark plug wires are going to the correct cylinders, and that 4 of the injectors (1,2,7,8 ) are correctly wired. The other 4 have different colored wires than the FSM lists however it's pretty obvious where they go.

Thanks Dan, that will be very helpful!

I'm going to add this link here, a bunch of high-res pictures of the various things around the engine. Nick, maybe the best I can do until I fly you out here.

If anyone wants to take a look, and if you see something weird, let me know...

[You must be registered and logged in to see this link.]

Hey I don't want to jinx it, but I think I might owe Fred K a kiss beer.

The black plugs and the black splats on the garage floor suggest incomplete combustion, and the smelly exhaust suggests plenty of fuel, and as Nick was pointing out both- along with the backfire- suggest weak spark. One cause of weak spark could be a bad ground, even though I repaired that over a year ago.

So I was reviewing my pictures and zooming in and really looking at it- I didn't like the way my ground at the ICM repair looked. I figured it wouldn't hurt, so I rearranged it such that the copper lugs were pressing directly against the ICM heatsink and not just clamped to the stud.

When I started the car up cold I could tell immediately that something was different, it fired up strong and idled really nicely. Throttle response was strong, and even after warming up it stayed running nicely. I got one "almost" backfire/blorpy sound, but other than that it ran better than I've ever seen it run.

I collected a log, I'll throw it up on the shared folder if anyone wants to take a look.

phantom 309 wrote:

because its seems to me that we are assuming you are doing everything right,..?

Lastly,.. have you carefully looked over the wiring harness?

phantom 309 wrote:

didn't this engine run fine till you changed everything around??

phantom 309 wrote:

Need to throw in a little freddy K advice here too,.  clean all your grounds on the head by the coil/module,.

make sure they are all hooked up and not 1 broken off in the bundle,..

lamune wrote:

Nick, the grounds are good. I redid those when I got the car, much better than what was there!

well done Fred,.

^^^Still choking on drink after reading this^^^ Good job,Fred....

phantom 309 wrote:

lamune wrote:

Nick, the grounds are good. I redid those when I got the car, much better than what was there!

well done Fred,.

You too Nick. And everyone else with the troubleshooting suggestions.

I'm still looking into why the timing on this motor seems to be well outside the norm when throttle angle goes over 30 degrees. Compared to other LT1 data sets it still looks weird. Any speculation as to what may cause this? Bad fuel? Knock sensors? Something else entirely? Could still be something up with the intake/vacuum leaks, I haven't had a chance to do that yet. (Had to wait for supplies to helicoil the stud on the oil cooler adapter!)

Good luck with that,...Fred will be able to help,.

andy caprice wrote:

Just to make sure I understand correctly (not being an english speaker); you mean a jerking forward motion, not the engine shaking the car? Mine did the former when it had a faulty egr valve. It was a new one. I don't know, if it was really faulty, or of wrong kind.

You have a Caprice in Finland? SISU!!

Ok, I got the car back together and was able to take it for a drive. No more oil pouring out of the front cover or the oil cooler, and that's definitely a good thing.

But onto performance- the hesitation I see when the car's sitting in park and I'm playing with the throttle is completely absent when the car is in gear and on the road. You can stomp the pedal from a dead stop and the car just goes. And it goes better than I ever remember. Those Flowmasters are really something, the car really sounds like a Camaro when you get on it.

It's not quite perfect, I can definitely feel something missing or not working correctly when the converter's locked up and cruising at a low speed (45mph or so) on level ground. That seems like a common EGR problem complaint. I'll have to get some logs I guess to see if anything points to a suspect there.

I'm checking other engine grounds to be sure they're OK too. What's the one on the front of the alternator on the alternator support bracket supposed to look like? I'm not sure that one is installed correctly.

Well, if anyone else is still watching, I got to changing the intake manifolds yesterday. No change in the car's behavior except the oil stopped pouring out the ends of the block. (a definite improvement there)

Car runs the same. It's driveable, but I wouldn't consider it enjoyable.

And yes I can make it backfire under the right (wrong?) conditions still.

I did replace the ECT. Testing with the chart and ohmmeter, it seems fine. The computed temperature values read by software agree with ambient readings, and the hot temps look to be in-line. Wouldn't hurt to re-evaluate, I have an infrared thermometer around somewhere I could use as a cross-check.