Rough idle, barely runs 94 6.5td
 

Just replaced cps and reinstalled ds4 (attempted db2 swap) drove the truck to the store this morning and it ran great, started right up and no problems. It sat for about an hour, came back out and it fired right up, pulled it into gear an went to pull out and it bucked once then rpms went to 400ish and it wouldn't take any throttle. I pulled it into neutral and revved it and sputtered and never got over 2000rpm. Swapped pmds, checked grounds, reset computer, checked lift pump, bled lines, an checked codes. I got a cps error as well as cylinder balance fault errors. Still same problem. Any thoughts? :argh:

Have you done a TDCO (pump timing) reset?

The OBDII trucks will do it automatically (if I remember correctly) every 50 start cycles.

I can't remember how the OBDI trucks do it, or if they do it at all. They may just run off the stored value until it's initiated by a scan tool.

I dot have a scanner or the cable to use my laptop. I tried disconnecting the batteries for awhile but to no avail. I ended up driving it home. I pulled the optical sensor connector and it still ran like crap but it allowd me to get over 10mph. I didn't turn the motor when I replaced the crank sensor. Just pulled the old one out and put the new one in.

The CPS replacement isn't the problem, I'm betting it's removing and reinstalling the DS4 pump.

Here's the thing; as little as 2mm of movement (the thickness of two dimes) on an IP can throw the timing out on a DS4. You're still not safe with less than 2mm, as that also changes the TDCO value.

When you pulled the Optical sensor, you forced the PCM to go to a base timing table and that's why the truck at least ran. It's a sort of "get you home limp mode" built into the PCM.

In order to set TDCO (TDC learn) and confirm base timing (TDC set) on an OBDI truck you need something like this:

Engh Motors - GMTDScan Tech

I know it sucks that you need to buy something to fix the truck, but you need this kind of stuff with electronic injection vehicles. Any of them. It's really no different than needing to buy a specific socket to get a wheel bearing off. You need the right tool to do the job....

OBDII trucks can be done with a key on-key off procedure. Unfortunately, that's not an option for your truck.

Unless you scribed a line on the pump and cover before you took the pump off and lined them up exactly when reinstalled, you don't know where you are for timing of the injection event and I'm betting you're "off" just enough.....

About all I can offer you is to ensure your pump is installed "straight up" (FSOS should be straight up). This should at least get it running halfways decent if TDCO is your problem, but you still need to have the PCM relearn the TDCO value. It changes every time you turn or remove the pump. Disconnecting the batteries will not clear the value, it's stored in non volatile memory.

Then, get yourself a bidirectional scanner (like the one I linked above) and set it properly.

Hopefully, that's your issue.

Other than that, you've either got a failed component on your hands or something is installed incorrectly....

Did it run properly before you tore it all apart?

It ran alright before I took it all apart an I wasn't getting a stepper motor fault before but now i am. I did in fact scribe a line where It was set before I removed it. I was getting a stepper motor fault so I replaced the crank sensor and it ran great (I read somewhere online that a bad crank sensor can set a stepper motor fault) its a strong possibility that the pump could be off but would I still be getting these codes for crank sensor and stepper motor? I'm trying to limit the amount of money I throw at this since I have a db2 I'm going to put in as soon as I can figure out why it won't push fuel to the injectors. If the pump was of then I figure it wouldve ran like crap when I drove it yesterday. When I start it, it will run fine for about 10 seconds then go into barely idling and won't rev past 1500rpm.

This is information you did not originally give.....recheck every thing you removed/installed.

It may have initiated a TDCO relearn on you and that's why it now runs like crap but didn't yesterday. Mine did that once. Ran fine on a stored TDCO value. It initiated a TDCO relearn and started to run like crap. Little did I know someone had frigged with the pump before I bought it and it had been running on a stored value. Did a pump timing and relearn and all was good again.

But my truck is a 98 and is OBDII. Like I've said, I'm not sure if an OBDI truck will do a "spontaneous" relearn like an OBDII truck....

Take the top cover off the pump and clean the rack that shuts off the metering valve and is controlled by the little solenoid under the cap....the body will be full of fuel but the valve will not allow it into the pump if closed so no fuel to the injectors. The rack needs to slide back and forth freely....they gum up and varnish or time....

My apologies, I must've forgotten to include that. Guess that means something has failed in the pump then huh. Looks like visiting a pump shop is next step.......

Read my post again friend, I think I was editing while you were typing....:ouch:

Ah okay. The solenoid was clicking but when I pulled it apart it was nasty under the cap. I've got everything about clean and I'll reinstall to see what it does. Can the solenoid be bad and still make that clicking sound like its working?

Yup.

If the metering valve won't open, the solenoid will/can still "click" as it tries to move it.

You can see where the "fork" the solenoid moves connects to the rod/rack in the housing. That rack is what opens and closes the metering valve.

It has been known to gum up and /or varnish. Its alao been known to wear a "step" in itself in high mileage pumps. If you had a passle of old fuel in there, it's a fair bet it's just nasty and gummed up.

If the metering valve isn't open, no fuel to the injectors...no fuel to the injectors and.......well, you can see where this is going......


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Alright that makes since. Thanks for the advice. Is it common for those solenoids to go out?

I've had good luck running a can of Sea Foam on occassion for gunk clean up

Alright so I let the truck sit and think about what it's done the past couple days. I went out and let it run for a bit. Rechecked codes and now I'm getting code 34 stepper motor fault and 91-98 cylinder misfire. I'm confused because the other day I had a crank sensor error and others too. Can the stepper motor cause a cylinder misfire on all cylinders?

Here's my "somewhat" educated "guess":

Your timing is still out and why the truck runs like crap.

The PCM is trying to adjust the timing with what it has at it's disposal; The stepper motor.

But the stepper motor doesn't have enough authority since you are so far out on the intital pump timing.

The PCM then thinks the stepper motor isn't working correctly because it isn't doing what is being commanded.

Hence, the PCM is setting code 34; Stepper motor fault.

And now we're right back to the need for you to adjust your pump and set TDCO....

:pca1:

The only reason I don't think it's the timing is because it ran great that morning then when I went to restart it started acting up.

Already explained that bro.

Everything you have brought up here points to an incorrectly timed pump.

I could be something else, but not as likely as pump timing.

Your time, your dime, your call....


:pca1:

bring it to a shop ahve them read the pump timing it should be 3.5 degrees

thats probably what im gonna try to do today if the local shops dont want some aborbant amount of money to hook up a scanner.

update: only one shop within an hour and they want $179 just to hook their scanner up to it. i think ill pass. think anyone on here might have one and live in virginia/northcarolina area

You can buy a program called "car code" for around 60 bucks that will do it for your truck.

That would be great but isn't car code obd ii only?

Keep asking around. Here there are 2 differwent guys at 2 different shops that used to be heads of service at different dealerships. They know what they are doing and don't jab ya.

Yeah, scratch that. Forgot your truck is OBDI, car code is OBDII...

So I gave up on the db2 for the time being and ordered an aldl cable to set timing with my ds4 pump. I should be able to set it with that engh program but from what I read online it won't go into the mode if there are any dtcs. Anyone know if there is a way to "tune out" the boost solenoid and egr on the obd1 systems? I have dtcs from removing those when I made a manual boost controller and removed the vacuum pump.

Nope.

You need to have the PCM reflashed ("chip change" on an OBDI).

I think some guys get away with leaving the egr hooked up, but you're already past that point by the sounds of it.

And yes, you need to clear the DTCs or TDCO won't intitiate. Engine has to be up to temp also.

If you can find a PCM in the scrap yard that's already an L65 calibration, you may be able to plug that in and get away with it. That should work, but no guarantees....

Ive still got everything that I took off I was just trying to avoid putting it all back on. Guess ill cross that bridge when I get to it.

Just to make sure we're not chasing our tails here; the truck was running properly before you pulled the DS4 off right?

This isn't a problem that's been around before you tried to install a Db2 is it?

The truck ran fine before I removed the ds4, no problems at all now that I think about it. Guess I shouldve left it alone. I'm pretty positive that your right about the timing. I'll know for sure when I get the cable and hook it up.

finally got my cable in the mail and figured out how to set it up. i hooked it up to the truck and yall were right about the timing, it was about 11 degrees. im gonna try moving it around when i get another day off and see if i can get it to run.

10-4 tell us how you make out

I moved the pump around a bit and this is what I got.
Desired inj timing. - 7*
Measured inj timing - 7.4*
actual inj timing - 30.1*

Its still running about the same and throwing cylinder balance fault codes. I used the engh scan tech basic. ( dont have the full program yet) What to do next?

try this:
http://www.oliverdiesel.com/tech/timing.htm[/URL]

Isnt that what's used to time db2's? I'm using the ds4 because I couldn't get the db2 to push fuel.

yup, that's for a DB2.

DS4 obd I:

FYI: TDCO - Timing the DS4 Injection Pump

oops read it wrong i thought you swapped to DB2 not DS4 my bad

update, i got the full program from engh motors. i tried to do that ehole procedure but its still throwing cylinder balance faults and now i got a code 88 offset error.
desired timing 7
actual timing 7.1
tdco -2.02

what am i doing wrong?

not to sound dumb, but i thought the timing is 3.5?

i went back and read that how to again and it is suppost to be ~3.5. i tried to turn the pump but its at its limit. i took the timing cover off thinking the gear moved when i was changing pumps but the gears are lined up. possible that key sheared in crank?

ok so all the gears are good and no keys were sheared. guess ill put it all back together and see if maybe i put the injection lines on wrong or something. im at a loss as whats wrong with this thing.

Well, the timing is maxed out for sure.

Are you turning the pump in the right direction for base timing adjustments?

Turn to the passenger side is retard , turn to the drivers side is advance.

i got the timing down to around 3.5-4. tdco set at 1.5 so my code 88 went away. which way do i need to move the pump to get tdco to set a negative value? and im still getting cylinder balance faults and it wont rev and runs rough.

Negative tdco is to the drivers side....