Engine/Transmission (1994 - 1998) Stumble/miss.. updated

[JeppinHackSaw]

https://www.turbodieselregister.com/forums/showthread.php?t=180148



Put 370's in a perfectly running truck, now it misses under a load. At idle it doesn't seem to miss, put in gear and hold brake/throttle and it will miss @ about 1100 RPM's, again at about 22-2300 RPMs (VIOLENTLY shaking the truck)



Today, I put new filter in, cleaned the pre-filter and also checked the overflow spring (mic's @ . 532 inches).



Truck's stock w/ an air filter and gauges. Gauges drop off when it starts to miss. (egt and boost)



I've bled the heck out of every fitting that there is (injectors and returns)



I'm @ a loss here. After everything that I did today, it still does the EXACT same thing.



The idle is a little low ~700 rpms in gear w/ the brakes on.



I'm going to read up on how to adjust that right now, but, I don't think a low idle will cause it to miss under acceleration.





Also, if you blip the throttle @ idle the truck will stall. . whether its warm or cold.

 

[JeppinHackSaw]

Well, RBratby is gonna come time it for me next week, apparently that's the issue. .

2nd or 3rd person that has said the same thing. Guess we'll go with that... chuck from New Era told me the same thing... others have told me timing won't affect it. . we shall see.

 

[PKemp]

The 370s you just put in... ... Are these new, rebuilt or used injectors? Poorly seating used injectors with weak springs could cause this and a "bad" spring would give the appearance of a timming problem because it would "pop" too soon. Did you remove the injector lines to change the injectors or just "move" them out of the way? Even a slightly "bent" line will cause a problem. If you removed the lines did you take out the intake airhorn also? If so did you reuse the old gasket or not? Did you re-seal the intake horn bolts? Did you clean out the injector holes good before putting the 370's in? They need to seat good, specially the 370's. Did you account for all the copper washers on the end of the old injector's? Did you reuse the old copper washers or put new ones in? There needs to be a very good mechanical (heat transfer - copper washers) connection between the injector nozzle face and the head or "hot" spots will occur leading to bad carbon buildup. If so, what thickness? 370's, unless special cut (they have a bad spray pattern for our engines), dump a lot of fuel but you should have a 913 pump which should be an adequate supply and since they are EDM's should have come with the right thickness washers. But a "double stacked" washer would be a problem here. If it was running "perfect" before, timming isn't causing this. Specially if nothing else was done. Check fuel pressure going to the injector pump from the fuel pump too. Have the rubber lines running behind the injector pump ever been changed ( if not replace them with marine grade diesel line)... ... . Changing the timming will help your top end but not your bottom "around town" end. It will also help with your EGT's (run cooler). Those 370's will run your temp gauge up fast specially under a load. Also with more fuel youre gonna need more air... ..... Sorry for all the rambling..... Been a hard day, need to go home and soak up some chilli 'n suds..... !!!!



So you have a 913 pump I think, you should be able to supply enough fuel to those 370's but check fuel pressure to the pump. Check the fuel lines behind the pump (replace if they have never been replaced before anyway - use marine grade diesel line). If fuel pressure is low replace the fuel return valve.

If this doesn't seem to do any good I'd be looking into those injectors. Have them "pop" tested. I'd make sure all this was good before I changed the timming. Once thats settled you can make timming mods. It was running "perfect" before the 370's and its running "lousy" after the 370's ..... hmmmmmm... ... ...

 

[WBerry]

I Put 370s In Mine And Set The Timing To 15. 5 Degrees And Had Some Tuning On The Pump Also. ive Not Had Any Miss,however It Will Stall When Cold If I Let Up On The Throttle Quickly,once Warmed Up No Problems.