Proper way to time an injector pump?

[LeadHead]

Got a quick question for you guys.
The ongoing saga of my '98 Suburban continues. After having it at the dealer to have it timed a week and a half ago it has never ran the same since. Saturday a private mechanic who has done most of the work on this vehicle before I bought it told me that if the dealer attempted to time the injection pump with the truck running that it would damage the pump. Rather, he said that it has to be done with the truck turned off. Can any of you verify this information? My friend and I (in case I need a witness) are planning on stopping by the dealership this afternoon to politely inquire how it was done. If this indeed the case and if he attempted to time it while running, it appears that the visit cost me quite a chunk of money. Any advice would be appreciated.

[gmctd]

I'd seriously consider opting for another mechanic - the 6.5 EFI timing is electronic, and must be checked with an OBD2 bi-directional scanner, with engine running.

If Inj Pump requires repositioning, a good mechanic can do that while engine is running, but most don't as it is not necessary.

That mechanical adjustment was done with engine running on the assembly line.

After the IP has been rotated and locked, the timing is again checked and adjusted electronically with engine running.

However, as the EFI 6.5 is a scary entity to most service departments, the service guy may be very unfamiliar with exact technique - it's sorta the luck of the draw, whether he gets it right, or not.

Have your timing checked for -0.5deg TDCO, which is factory spec - if the service guy appears to be savvy, ask him to set it for -1.5deg TDCO, for that enhanced driving experience

[JohnC]

The deal is you should not adjust the pump while it is running. The load on the drive gears is to great to safely loosening the pump. It's unlikely they did it that way.

[gmctd]

It's a matter of techique, John, but you're right - the average mechanic should not be loosening the IP while the engine is running, particularly if he doesn't posses the spanner for Stanadyne IP's.

It is highly unlikely they adjusted the IP with engine running.

My point was, and is, the guy obviously doesn't know his subject, and shouldn't be advising others, or be allowed under the hood of this fragile beast.

Sounds like the typical scam for some very expensive, very unnecessary work.

[rjwest]

96-2000

1st, you need a 'scanner' or tech 2 , something that will read the stored data
in the pcm. I use the CarCode ( obd-2.com ) and a laptop.

Your are looking for the TDCO value.

2nd, do the Key on/key off routine to clear the current TDCO,
* pedal to the metal,turn on ign(don't start eng ) wait 45sec in this state.
Turn off ign, release pedal, and wait 30 seconds. TDCO should know be
'0', check scan data to verify


3rd, start engine, when the coolant temp reaches 170 degrees, PCM will
set the timing. ( you will here the TDCO being set by engine noise changing)
Check scanner for value,
( search posts for reccomended /TDCO values )

If TDCO not within acceptable range, than with engine off, rotate pump
1 mm at a time and repeat, step 1 - 3....

see posts for mechanical adjusting of inj pump procedure

[LeadHead]

Let me back up a little bit and offer some clarification, here. This is the Suburban that received the timing chain/gears, harmonic balancer and water pump swap by my buddy & I. After the swaps, the truck idled and ran very well except it had a loss of power and would bog down under a load. I took it to the dealer to have the IP timed and after zero'ing the TDCO the truck ran absolutely horrible, in fact, undriveable. They decided that the timing chain must be off by one tooth, because it was off by about 20 degrees, and also told me that the vacuum pump was bad which would explain why the turbo never seemed to kick in for me. We had it towed to my buddy's place, verified that the chain was off a tooth and that the vacuum pump was indeed bad, and fixed both items. After doing so, we started it and it still ran horribly so we had it towed back to the dealer and they never could get it to run right again, then told us that the pump must be bad.
Fast forward to this last Saturday. Though this is my first time to deal with this mechanic personally, he has serviced this particular truck in the past when my friends owned it, along with other vehicles of theirs and they say that he has always treated them right. He knows this vehicle, took a look at it and told me that he thought that the dealer was correct in saying that the pump was bad and then told me about them possibly ruining it if they timed it while running. Before even looking at the vehicle, he did inform me that he uses a Tech-2 for these jobs.
Anyway, this is not a blind defense of this guy, but I really don't think he was trying to take advantage of me.
Here are the current symptoms:
1. It's quite difficult to start the engine cold, and when it does start it feels like it's running on about 5 or 6 cylinders even when warmed up, and shakes the whole truck. The idle speed is 1400 rpm and will hold you at a steady 34 mph if you let it.
2. If you so much as touch the accelerator, the engine leaps from 1400 to 1800 rpm and smooths out perfectly. This happens either in park/neutral or while driving.
3. If you hold the accelerator pedal at 1800 or 1900 rpm, the truck will smoothly accelerate up to about 50-52 mph without the tach needle wavering.
4. It will hold this 50-52 mph at a steady pace on even ground or a slight incline. If there is a downgrade, the engine wants to drop into 3rd gear then bucks and jerks until you take your foot off the pedal.
5. If you take it really easy, you can get it to hold steady at 65, but if you push it a little too much then it drops into passing gear, spools up and takes you up to 90mph before you know it. Taking your foot off the pedal makes it start bucking again.
Would a defective PMD cause these symptoms or does it seem more like the pump itself? I'm leaning towards the pump myself, but this is the first diesel I've ever owned and it's an all-new experience for me.
Thanks again for you guys' help.

[65TD]

Are there any codes in the PCM?

[LeadHead]

I do not have a scanner to check it and live 20+ miles from town. The check engine light is not on, which it had been before changing the vacuum pump, but that is no guarantee, right?

[65TD]

It's hard to say what's in there without checking.

It would go a long way toward figuring out where to start looking.

[damork]

One is never to rotate the injection pump while engine is running. I know of cases where it was done on farm tractors leading to the head and rotor seizing in the pump and the mechanic being seriously injured.

[gmctd]

FYI - the IP has a machined collar on the flange which fits into the machined timing cover bore perfectly, preventing any pitch change when the TC nuts are loosened just enough to rotate the pump.

The tension of the 8@ 0.255"od x 0.109"id thick-wall steel injector pipes prevents the IP from turning under reaction to pumping-torque when the engine is running.

The spanner for the Stanadyne DB and DS IP's permits rotating the IP 2mm while the engine is running, allowing the tech to also manipulate the Tech2 - locking one nut holds the IP in the adjusted position securely enough to test-drive the vehicle.

Matter of technique, folks. :cool:

Thanks for that refresh, LH - I needed that.

We've just heard many similar horror stories over the years, after the owner lost 2-3k on unnecessary repairs, so no offense, dude - just simple caution

You may have couple injector pipes crossed - iirc, someone posted the diagram awhile back.

[TAG]

I wonder if 1 tooth off on timing gears is enough to tap a valve or two, bending them & dropping compression on some cylinders?

[gmctd]

A compression check will reveal that, so would be in order for diagnosis.

[LeadHead]

No offense taken, gmctd, that's why I came here for advice.
As for dropped compression, he said he tried deadening each cylinder and it did not affect the way it idled. Forgot that one tidbit when I posted the original message.
Also, even with the gear off one tooth, the truck idled and ran perfectly smoothly except under a load. Only when I took it to the dealer did it then totally take a dump on us.
As for the crossed pipes, would there have been ANY reason for them to disconnect them simply for the timing procedure for which I took it to them? Man, I thought it would be a simple matter for them but I guess I was wrong. However, I realize the responsibility of the off-tooth timing chain rests on my shoulders ultimately.
One thought I had; would the way it was running horribly (as a result of them setting it to 0 TDC while the timing chain was wrong) possibly cause the pump to fail? As far as I know that pump could have easily had way more than 100k miles on it.

[gmctd]

No, not possible - but failure in a 100kmi pump is possible, under any circumstance.

Beginning to sound like Fuel Solenoid failure - is the SES turning on and off? STS?

Could also be a load of really bad fuel or water in fuel - that usually results in black smoke with misfiring and shaking and such.

Have you got a pc-laptop with USB2.0?

[LeadHead]

Would those items account for the truck running pretty much perfectly at 1800-1900 rpm? Yes, I have a PC laptop with USB 2.0.

[rjwest]

GET A SCAN TOOL. You are only guessing, without one....
Guesses cost MONEY....!!!!

[LeadHead]

Yes, I can see the wisdom in that advice, thank you! For the budget-minded, occasional user which one should I consider? Should I get a standalone unit or one that connects to a laptop, or can you use them either way?

[gmctd]

The Fuel Solenoid can cause those symptoms - crossed injector pipes can can cause appearance of smooth-running at some rpms until loaded, then the bucking and jumping.

You could pull the IP and have it tested, also the 100kmi injectors - the PMD would cause stalling\misfire to dead\no start.

[LeadHead]

If there is a diagram online that shows the order the pipes should be connected, that would be nice. Is it reasonable to expect they would have disconnected them at all just to time the pump?

[arveetek]

If there is a diagram online that shows the order the pipes should be connected, that would be nice.

Check out this thread (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=26208). About halfway down there's a diagram showing where the injector lines should connect to the back of the pump.

Casey

[LeadHead]

You da man, thanks! Will have to check the lines when I get home tonight.

[Shikaroka]

2nd, do the Key on/key off routine to clear the current TDCO,
* pedal to the metal,turn on ign(don't start eng ) wait 45sec in this state.
Turn off ign, release pedal, and wait 30 seconds. TDCO should know be '0', check scan data to verify


Hey RJ,
Should this (Step 2) be done with the engine cold?

[rjwest]

step2: I don't think it makes any difference, It will clear TDCO, at least in Florida it will.

But If it is real cold, It may be a good Idea to warm the engine first ,
as I am not sure how it affects advance for cold start,
I believe it still will advance and start engine, but in REAL cold weather,
probably not a good Idea to clear TDCO untill warmed up...

[Shikaroka]

I asked, since you need to let it warm up to 170. What happens if you clear the TDCO and the engine is already above 170?

[gmctd]

Purpose for having ECT above 170deg or at operating temp is to ensure PCM is not demanding cold-advance - you'll get better results if IAT is also above 70deg

[rjwest]

Sorry< If it is at 170 degrees , the tdco will occur as soon as engine is
started,
When I adjusted my timing, I let the engine cool down before moving the pump.
Too hot for me, Coolant was about 130/140, as soon as 170 reached,
tdco calibration was cmd'ed by PCM,,,

I liked this procedure, it took some of the mystery out of the process....

[kenisret]

Section 4-24 of the 1995 service man. states eng. must be shut down while pump is moved to prevent eng damage