Shaky idle and codes

[1994ch]

My 94 has a slight shake at low speed............its noticeability fades out above 1200 (might still be there)

I get a code for cylinder imbalance #1 (code 97)
Another (or maybe related) that I have noticed once or twice over the last month is an occasional code 36 injection time long (when I clear it, it stays out for quite a while) but its presence does make me worry about the IP

I have the clear line on the IP return and do not get bubbles.

Does this sound like an IP or an injector issue?

Thanks!

 

[Will L.]

Swap that injector with one from the other side of the engine and watch if it follows the injector or stays at the cylinder.

 

[1994ch]

I swapped injectors and the codes did not come back although the shake was still there (just not quite as bad as before) I will drive it for a day or so and see if the codes come back......

 

[1994ch]

The code came back...........still #1. When it starts up stone cold (first start in the morning) it chuggs a lot of white/gray smoke. For the rest of the day even after sitting for several hours it starts up fine.

 

[ak diesel driver]

Try unplugging the ECT sensor in the coolant crossover next time you start it cold.

 

[1994ch]

So I unplugged the sensor and started it up this morning (73* this morning). Fired right up no smoke, I jumped out and plugged the sensor back in and it bogged down and chugged a little smoke. So does this mean a bad sensor? Or something else? Is it the same part as the other temp sensor or is it called something else?
Thanks!

 

[ak diesel driver]

It is possible the temp sensor is bad but more likely it needs a new IP. I had one do that and bison had one like that. Upon tear down of a couple of IPs he found the advance plunger at the bottom of IP had corrosion in it. It's the lowest part of the IP and water can settle down there with no way to flush it out. I read about someone mounting a switch that effectively unplugged the sensor and ran theirs for a long time like that as it only was an issue during cold start.

 

[1994ch]

Would this explain the cylinder imbalance as well or is that just another sign of the IP being worn out?

 

[ak diesel driver]

IDK but I would deal with the IP first and see if it goes away

 

[1994ch]

So if I pulled that advance plunger out and swapped it with another plunger I have from an older pump that I have on the shelf would that fix the problem? Or is the corrosion on the internal major parts of the IP?

I pulled one of my old pumps apart last night and the advance plunger did not seem to be corroded, and looked like it might be an (dare I say) easy swap.

 

[ak diesel driver]

That's out of my area of expertise.

 

[1994ch]

Another thing I noticed....... I plugged into GMTD ScanTech and shut off each cylinder one at a time. When turning each cylinder back on it would immediately run smooth again, all except for #1 cylinder, which would keep a slight stumble for 3-4 seconds before running smooth. (and when I say "smooth" I mean as smooth as it has been getting since this problem started.)

 

[Will L.]

Compression test.
If cylinder 1 comes out same as others, point finger at the ip. (Unless a damaged injection line could be blamed.)

 

[1994ch]

So I ran a qt of ATF through it and put a bottle of Diesel Fire in the tank....... hope I don't jinx myself but so far it seems to have cleared up. I am sure it will probably come back but it would be great for the budget if I could get my tahoe up and running before I have to shell out for a new pump.