• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Timing All Messed Up

A

allanh

New Member
Messages
11
Reaction score
0
Hi Folks,

Anyone know if the IP timing stepper motor should move up and down at all times or only when engine over 170F and/or doing a TDCO relearn?

Because I'm thinking the fact that my TSM doesn't move at all might explain why the timing is all over the place - idles poorly when cold, and when hits 170F blows lots of white smoke.

I just replaced the IP and mounted it pretty close to straight up, with the flange just a little to the driver's side of the wedge on the timing cover.

Any ideas would be great as I'm out of 'em.
 
Do you have access to a scanner to look at the PCM sensors? Did you install a new IP or where did you purcahase rebuilt? What was symptom of old IP?

Sometimes rebuilds come with the OS not calibrated correctly, and sometimes they come with components that dont work. A scanner would be easiest way to see whats going on and run the TDCO timing procedure to make sure the PCM knows where the IP is positioned. What year and model is the truck?
 
Yes, I do have a scanner. What I saw was when cold (under 170F) desired = actual timing. Then 170F hits and actual drops to 2 or 3 degrees and it starts smoking like crazy. Old IP symptom was hard/no starting while warm until I poured cool water over it. Then it would start. The rebuilt pump I bought from a member on a forum.

I did do the TDCO and it goes right to +2.46 and stays there, even after resetting to 0 by unhooking the batteries.

This is a '99 Suburban.
 
What are the desired and actual timing values on the scanner when cold and warm?

The IP probably needs to be moved more like 6mm to the drivers side if everything is working right.

However, if you alredy placed it to where the IP flange corner was to the drivers side of the timing mark, then maybe you have a timing reference issue. Try unplugging the Crank Position Sensor (CPS) and see what happens. You cant run TDCO and youll get a code, but see if it runs better. Had you swapped the CPS at all? If that doesnt improve things, then try unplugging the Optical Sensor (OS) on top of the IP and run with the CPS.
 
Ok, actual and desired are 12.5 degrees cold. Then at 170F desired is same, but actual is like 2 or 3 degrees.

Yes, it has been as far as 2 mm to the driver's side of the timing wedge. At that point the FSO was leaning slightly and 1/2 inch from the rad hose.

Have not swapped the CPS but did remove the timing cover and did some work in there.

buddy said:
What are the desired and actual timing values on the scanner when cold and warm?

The IP probably needs to be moved more like 6mm to the drivers side if everything is working right.

However, if you alredy placed it to where the IP flange corner was to the drivers side of the timing mark, then maybe you have a timing reference issue. Try unplugging the Crank Position Sensor (CPS) and see what happens. You cant run TDCO and youll get a code, but see if it runs better. Had you swapped the CPS at all? If that doesnt improve things, then try unplugging the Optical Sensor (OS) on top of the IP and run with the CPS.
Click to expand...
 
Something tells me the CPS and OS are conflicting, but it will run off just one if you unplug the other, but put you into a limp mode, but still driveable.

There should be some cold advance when its cold, like below 120F, so desired should be higher when cold than when warm. Are you reading the coolant temp on the scanner, because it should change if the PCM is seeing the temp changes. Unless a TDCO DTC is causing it to be screwy like that, are you getting a timing DTC?

That and it should not be 12.5 degrees at warm idle, what are the idle rpms? When you run the TDCO learn, can you see the lowest actual timing falls to? Unplugging the battery should not reset the TDCO back to 0, but it might clear the DTC for TDCO being out of range, until it sees that its wrong again and the DTC should come back.
 
Yes the coolant temp does change on the scanner. Did get a p1214 at one point but since moving the IP has not returned. Idle rpms are around 600 but if you tap the pedal rpm jumps and stays at 1100 until you put it into gear.

I'll have to try pulling the CPS and OS connectors tomorrow and see if any improvement. It's hard to get to the point of doing a TDCO relearn because once it hits 170F it smokes the neighborhood out and so erratic it sometimes dies.

buddy said:
Something tells me the CPS and OS are conflicting, but it will run off just one if you unplug the other, but put you into a limp mode, but still driveable.

There should be some cold advance when its cold, like below 120F, so desired should be higher when cold than when warm. Are you reading the coolant temp on the scanner, because it should change if the PCM is seeing the temp changes. Unless a TDCO DTC is causing it to be screwy like that, are you getting a timing DTC?

That and it should not be 12.5 degrees at warm idle, what are the idle rpms? When you run the TDCO learn, can you see the lowest actual timing falls to? Unplugging the battery should not reset the TDCO back to 0, but it might clear the DTC for TDCO being out of range, until it sees that its wrong again and the DTC should come back.
Click to expand...
 
Check the warm idle fuel rate, maybe the OS was not calibrated correctly and youre basically bouncing around 0mm^3. It should be about 8mm^3.
 
So, the fuel rate when engine warm should be around 8mm? Cause I'm seeing 0-1, 2.5mm max. If that's not right, then is the OPS bad or just uncalibrated?
 
Ha, someone must have just swapped the OS without realizing how important its placement is.

Just uncalibrated is all most likely, seen it multiple times, you can correct it, I put some details in the attached file, first page.

Basically you have to bump the Optic sensor to where its about centered, put it back together and then check to see what the warm idle fuel rate is to see if its right. Yours is worse than most I have read about, as they would jump around from like 0 to 3. 6-9mm^3 at idle is a good target that will run well.

I purposely make the engine lope at idle by doing a similar thing in the PCM, so I can imagine yours is usually on the brink of stalling, constantly unbalanced.

Here are some websites of help as far as the actual accessing the OS and what youll see.

http://www.mamut.net/royh/newsdet9.htm

This thread was actually about how to do purposely (to a lesser extent) what you want to undo....
http://www.dieselplace.com/forum/showpost.php?p=332796&postcount=19
 

Attachments

  • Mnx&Mods info_2.5-small.pdf
    1.4 MB · Views: 21
That's some good stuff there Buddy. I've got some reading to do now. :)

I got the problem solved! You were on the right track with fuel rate. It turned out to be the PMD - it was missing the resistor! I must have forgot to put it back in several months ago when I started the engine overhaul project and was testing with another PMD.

Just amazing that a little piece of plastic with a resistor can make the engine go from erratic and shaking the whole truck to smooth and normal sounding.

thanks for your help,
Hank
 
Hmm, thats peculiar as a resistor missing should not cause that problem, just set it to a default setting, and you should have gotten a code for it after running TDCO.

What may have been happening is that the connector was simply loose without the resistor in. Does the fuel rate now read right and TDCO was able to be set correctly?
 
If he hadn't completed a TDCO, then it would not have done a resistor check yet. I was gonna say check your resistor when I started reading teh thread, but got down to the bottom and seen you had already found it.
 
I was able to set the TDCO before finding the missing resistor. Once set it was clear something else was causing the bad symptoms because they remained: erratic idle, shaking and bumping of the whole truck and horrible pedal response. Only the smoking went away once TDCO was in the good range. So the lack of resistor wasn't preventing TDCO set, but was complicating things.

I'm going to check fuel rate later just to compare. I did look back at some scans from a few years ago and indeed the warm idle rate was around 8mm.

buddy said:
Hmm, thats peculiar as a resistor missing should not cause that problem, just set it to a default setting, and you should have gotten a code for it after running TDCO.

What may have been happening is that the connector was simply loose without the resistor in. Does the fuel rate now read right and TDCO was able to be set correctly?
Click to expand...
 
Looking back it seems the cause of not being able to set the TDCO was probably because in the beginning the pump was too far retarded. Then, when it was in the right position, I didn't complete a relearn because once it warmed to 170F the engine would either stall or blow smoke so badly that I'd shut it down cause it would set off the garage smoke alarms and tick off the neighborhood.:hihi:
 
Wait, don't go away yet Buddy.:hihi:

I rechecked my fuel rate and now it is too high at idle. It is about 16mm warm idle and idle is about 680-715rpms. Also making a slight rattle or knock. Do i need to do a relearn after putting the resistor in the PMD? Maybe the ECM doesnt know it is a 5 value.
 
Yeah, you need to run TDCO learn to learn the resistor value. Although its odd that its that high. Is there anything peculiar about the fuel that you use?

What is the warm idle timing at now? It probably went down since setting a valid TDCO value.
 
Hmmm, using regular diesel as far as I know.

Warm idle timing is now 11.5. Did a relearn and that didnt change but TDCO went from -0.79 to -1.41 without moving pump.

Fuel rate still around 17mm. Maybe OS not calibrated?
 
After reading this thread the EE in me comes out. I am thinking if I could take a oscilloscope and trigger off the crank sensor while looking at the IP OS and crank it over, measure the time, then do some math I could set the OS position like it should have been on the IP test stand. I realize not everyone has a scope handy, piggy backing into the connectors is a pain, but it should be doable. If you wanted to set the OS out of the truck, a cheap test stand to do this on could be made from a junk block with a crank, flex plate, starter, cam/IP drive, crank sensor, some wiring, a few parts to energize the sensors and nothing else. Yea I'm nuts.
 
You must log in or register to reply here.
Back
Top