Engine/Transmission (1994 - 1998) popping and banging 95 12 valve truck

[CSnyder]

Ive got another friend with a 95 5 speed truck that is having problems with popping and banging under acceleration while sitting still or driving. He just had a new head (due to cracks) and replacement stock 215 injectors installed and it ran crappy before like it does now. The timing was verified as stock by TDC and pump timing at TDC also. It seems to clear up after it warms up some but still doesnt seem right. It also smokes white while doing this popping.



Thanks in advance!

 

[JoshPeters]

Check the fuel pressure. Id be willing to bet the fuel pressure is low.

 

[Forrest Nearing]

this is a timing issue... if you just pinned everything and installed it, your timing could be anywhere from 8-13*



use the drop-valve method and set timing between 16-17* and it'll clear it up

 

[CSnyder]

I have timing tools and confirmed timing at 13 degrees stock.

 

[Forrest Nearing]

is it stumbling/white smoking when this happens? is it more pronounced in lower gears? is it more pronounced when it's cold?



usually a lack of fuel just means the truck has no guts

 

[CSnyder]

yes it stumbles and smokes white when it pops and bangs. To me it seems to be a timing issue but I checked it twice for him now and got 13 both times. I havent driven it yet but I know its worse when it is a cold motor. Thanks for the ideas guys! Keep em coming please!

 

[Forrest Nearing]

13 is low... and the bigger injectors without bigger DV's will amplify the problem.



this is a timing issue, I promise you

 

[JoshPeters]

I've had 2 trucks that had 160pumps that were doing similar things that showed to be a fuel pressure issue. Granted the timing was 18 on them, but they would starve for fuel on accelleration. If it's got the "good" overflow valve, pull the spring and streach it out a bit and try it again.

 

[Grizzly]

Do you have gasoline mixed with you diesel? It could also be a cracked head or head gasket.

 

[CSnyder]

13 is low... and the bigger injectors without bigger DV's will amplify the problem.



this is a timing issue, I promise you

The stock timing is 13 degrees and it is a 5 speed truck so the 215's are a stock replacement injector. The only mod this truck has from stock is a BHAF.

 

[CSnyder]

Do you have gasoline mixed with you diesel? It could also be a cracked head or head gasket.

It has good clean number 2 only in it and the head was just replaced with a new one. It ran rough before he took it in.

 

[Garbe]

Check for water in the fuel at the fuel filter.

 

[CSnyder]

Check for water in the fuel at the fuel filter.

done this a few times already to check for gas in it.

 

[Forrest Nearing]

The stock timing is 13 degrees and it is a 5 speed truck so the 215's are a stock replacement injector. The only mod this truck has from stock is a BHAF.

a 95 is a 175hp engine. And it has different injectors than the 215 engine.



by all means, keep chasing the issue and throwing parts at it... but if a fuel pressure test verifies good supply pressure, I promise you bumping the timing to 16-17* will not only improve mileage, but it will totally cure your issue if you've got a stock turbo.



how are you finding TDC on the engine? I highly recomend using the drop-valve method to find true TDC and then verifying plunger lift. I suspect that you are below 13*, but EVEN AT 13*, these symptoms don't surprise me.



my '97 wan fine untill I put an HX40 on it... after that, it would pop/stumble/etc. at heavy throttle with light load (let me guess, your friend's truck doesn't break up like this if you lay on the throttle in higher gears starting at a low RPM?)



I couldln't figure out what the problem was... it was horrible in the cold, and it was HORRIBLE at high altitude, and it was downright painful at high altitude in the cold!



dyno'd the truck, and it was 20-30hp less than what I anticipated it should be.



I ACCURATELY checked the timing using the drop valve method and a dial indicator and found that the timing was at 12* and NOT at the 16* I was told it was at.



I bumped the timing to 16. 5*... cured ALL of my stumbling/drivability issues, picked up 2mpg on the highway, and lowered WOT EGT's by over 100*



YMMV

 

[BigPapa]

The stock timing is 13 degrees and it is a 5 speed truck so the 215's are a stock replacement injector. The only mod this truck has from stock is a BHAF.

If you're using the lift specs for a 215 to get your timing, that's your problem. 4. 98mm lift for 13* timing on a 215 pump isn't even on the chart for the 175 pump. I'd estimate it's somewhere around 7*-8*.



Look here:



Diesel Timing



for lift specs on your CPL number.



Scott

 

[CSnyder]

turned out to be a bad lift pump. he had to have it to haul cows and took it to Cummins today.

 

[CSnyder]

they also verified timing at 13 degrees. I did fail to mention it has a replacement 98 motor in it. He scored a piston 2 years ago and just dropped a complete motor in it.

 

[BigPapa]

Glad you got it figured out.

I did fail to mention it has a replacement 98 motor in it.

That would make a difference.



Scott

 

[JoshPeters]

Glad to hear it's back on the Road Chris.



Glad I could help.