Detonation?

[jhill]

This all happened very quickly so I did't have any time to react other than to save the car from spinning out. I was driving home and it was wet out, I pulled through second gear out of a lazy corner and all of a sudden the tires broke free, the engine shot up to redline and I had all I could to save it. I know it wasn't really a good idea to come out of a wet corner like that but I can't change that now. All I have is a narrowband crap afr gauge that doesnt really work correctly to begin with, but all I caught out of the corner of my eye was alot of red meaning it was leaning out. (Although the gauge always is off and changes when you draw off the battery like when the headlights are on so I can't asssume it's very trustworthy.)

 

Anyways, I pull up to a light about 500 yards down the road and bam, the car starts sounding like I'm only running on 5cylinders or something. So I take it really easy until I can pull into a parking lot. I figured one of the injector connections came loose, I've had that happen before ( I really need to get new connectors for the injectors, they're pretty shot). Nope, everything good.

 

So I took it up and down the street today, same stuff. I did a compression test on it and the numbers are much lower than the original test I took 6months and only 100miles ago. Those numbers ranged from 139 to 145. The new ones came in 105 to 120. Now when this all happened I didn't hear detonation, and I get no knocking, no unusual smoke, just runs really rough, has a decent vibration that seems like it's coming from the engine, not from the u-joint that needs replacing, And the turbo sounds great until it comes down off spooling up and then it sound like the blades are scraping on the inside of the housing or something.

 

So, did I grenade something? Time for a rebuild or just more troubleshooting? Any input is greatly appreciated. Criticism too, I can take it.

[KyleG]

This all happened very quickly so I did't have any time to react other than to save the car from spinning out. I was driving home and it was wet out, I pulled through second gear out of a lazy corner and all of a sudden the tires broke free, the engine shot up to redline and I had all I could to save it. I know it wasn't really a good idea to come out of a wet corner like that but I can't change that now. All I have is a narrowband crap afr gauge that doesnt really work correctly to begin with, but all I caught out of the corner of my eye was alot of red meaning it was leaning out. (Although the gauge always is off and changes when you draw off the battery like when the headlights are on so I can't asssume it's very trustworthy.)

 

Anyways, I pull up to a light about 500 yards down the road and bam, the car starts sounding like I'm only running on 5cylinders or something. So I take it really easy until I can pull into a parking lot. I figured one of the injector connections came loose, I've had that happen before ( I really need to get new connectors for the injectors, they're pretty shot). Nope, everything good.

 

So I took it up and down the street today, same stuff. I did a compression test on it and the numbers are much lower than the original test I took 6months and only 100miles ago. Those numbers ranged from 139 to 145. The new ones came in 105 to 120. Now when this all happened I didn't hear detonation, and I get no knocking, no unusual smoke, just runs really rough, has a decent vibration that seems like it's coming from the engine, not from the u-joint that needs replacing, And the turbo sounds great until it comes down off spooling up and then it sound like the blades are scraping on the inside of the housing or something.

 

So, did I grenade something? Time for a rebuild or just more troubleshooting? Any input is greatly appreciated. Criticism too, I can take it.

 

Ive got a carb'd Z myself, and I took a shot tuning it for the first time. I thought I had everything going good so i took it out for a test drive, but after a few minutes out, it started to sound like garbage; it was running really lean and popping, then it started to sound as if it was running on 4 or 5 cylinders, much like yours. So I brought it home and after a few hours of trouble shooting i noticed that some of the sparkplugs in the non firing cylinders had a brown coating on them and wouldn't fire when switched them around. A new set of 6 and a re-tune had me going good.

 

To sum up, check your plugs, I know it wouldnt affect your compression, and that there could be something more serious going on, but hopefully it will at least get them all firing again.

 

Good luck

Edited May 30, 2010 by KyleG

[jhill]

Phew. Got the car back to normal. Cylinder 5 was not firing at all, the wire like burned itself up and the connector to the spark plug was broken. Alson on 5 the injector wasn't firing because of all of the buid up on the metal part of the connector.

 

It was just really wierd, too coincidental that it started running so badly right after a high rpm mistake like that.

 

I do think the turbo needs a rebuild though, ehh good time for an upgrade.

 

Oh and Thanks Kyle G