Hi all,
I'm new here, so please bear with me.

The story starts last fall when my IP pukes while going down the road. I towed it home, checked it out (I am a mechanic, although I don't specialize in diesels) then called the dealer to have the IP replaced under the special extended warranty campaign. I tow it to the dealer and they confirm bad IP and replace it with new and improved updated unit.

Truck is ready and I pick it up. Starts a little funny (like out of time gas motor) figure I'll give it a little time to relearn. Drive it for a couple of weeks, still starts funny AND it now gets 14 MPG. It used to get 17. I call the dealer and ask them if they would be kind enough to recheck everything (mainly timing and TDC offset). I explain the starting funny and the big dive in MPG. They take the truck and call me 30 minutes later to tell me it needs glow plugs. I ask what this has to do with fuel economy, and they say I am wasting fuel at startup. I asked if they recheck timing and TDC offset and they say no. I refuse the glow plug replacement ($12 per plug and 4 hours laboe to R&R).

I took the truck home and replaced the GPs myself with ACDelco. (Took 45 minutes in the driveway). Big suprise no change in anything.

Now with the questions;

Has anyone had a big drop in MPG after an IP replacement?

I have a snap-on mt 2500 scanner that I can use to read the timing. The desired is 0 and the actual is +3.5

I have good cranking RPM and both batteries are 1 year old bought and installed the same day

The TDC offset is -.64

Is there a better setting for MPG?

Why the funny starting? It will start unplugged at 0 degrees in the winter, it just sounds like a gas motor with the timing off, and cranks a little long. It sounds the same when it is warm outside or the engine is warm.

Now a note for the naysayers;

I have owned this truck for nearly six years. When I say it gets 17 MPG, I mean I drive it until it gets to a 1/4 tank, the trip meter reads between 450-500, and I put 27-30 gallons back in to fill it up. I check it regularly too. Before the IP I could just touch the key and it was running. Now it starts funny.

If this is the nature of the beast after having the 'new and improved' IP installed, I guess I can accept that. But I know it can start better.

Just for grins, I have checked or replaced the following parts;

Lift pump - rusted out and started to leak.
OPSU - lift pump runs koeo
glow plugs - at 84,000 miles starts a little better in the winter now
fuel filter - when lift pump was replaced

Sorry for the long story. Any words of wisdom would be appreciated.

Mike

If you can set the timing yourself and you have the tool, just do it yourself. At least you have a new IP.

Tooltym,

I have never seen a new injection pump that was built to the high side of the specs. I always thought new pumps were not ran or calibrated on an injection pump stand. The ones that I have seen checked on a calibration stand were always off on the calibration. Either the advance was wrong, or the fuel output was off. I would first get someone else to reset the timing. Try and get it above -1.00 and under -1.94. It is hard to get it exact. It can be done, but takes along time. If you know of someone that has a tech 2 scanner and they can show you how to do the TDC offset learn, you can play with it until you get bored with it. Most dealerships only give a small amount of time to install a pump and if it comes in spec, then the tech will let it go. Where is the PMD mounted now?

I can set the timing myself, but it appears that it is correct. I have a desired of 0 and an actual of +3.5

I have seen others with the TDC offset different than OEM spec, but I don't know why. My main goal is to get the MPG back if possible, and get it to start easier.

Mike

Toolkit,
Then PMD is alongside the plenum on an FSD Cooler. It has been there for five years. Do I timing below -1 or the TDC offset?

Depending on how you're reading that, those values are not even correct - Desired is where PCM wants OS to be, Actual is where OS is, and should always = Desired during normal operation - any DTC's?

gmctd,

No DTC's.

I am using a snap-on scanner in timing set mode. when reading data live, the timing varies between +14 and +16. When I go into timing set mode I get the 0 and the 3.5

Have you read the TDCO timing procedure I posted at an earlier juncture?
http://dieselplace.com/forum/showpost.php?p=2397612&postcount=1

and, for MT2500

http://dieselplace.com/forum/showthread.php?t=167826&highlight=tdco+learn

gmctd,

I read this one;

http://dieselplace.com/forum/showthread.php?t=2599

I will read yours now.

Ok, I'll wait.................

BTW, I'm a Spec Ed person, so making a practice of rereading my previous post(s) may help, at times

gmctd,

OK. Mine is OBDII, so I can do the koko to change the TDC offset which I did not know. I am seeing different specs and I guess I'm not sure which ones to use. I read in the other post that the snap-on scanner will not read the same as the T2, but the readings that I am getting are as I said earlier. Do I want the offset to read at -1.5 or the -5 or 6 like the other post says?

Thanks for all of the help. I just don't trust the dealer to tell me what the deal is.

ECT must be greater than 180degF, all DTC's cleared B4 you do anything - when there, note comparative timing, which should not be above +8.5deg - if there and stable, read TDCO value, post your numbers

ECT 185, no codes
timing in scan mode 11.9 desired, 12.1 actual
TDC offset -.64
timing set mode 0 desired, 3.5 actual
snap-on mt 2500 scanner

Am I looking for +8.5 during a regualr scan?

If you've read both the TDCO blurbs, you should know you are not to even think about
TIME SET, nor did I mention TIME SET - forget TIME SET - you need to do a scan, READ Desired and Actual timing and READ TDCO - FORGET TIME SET - TIME SET is not your friend in OBD2 - each time you do TIME SET, you're throwing things a little further off with that +12deg advance, which is not helping matters


I hope I'm being clear about that, because if you're doing Super Mario Bros on that keyboard as I'm trying to figger out what you have, we're taking two steps back for each no step forward - we're trying to establish a baseline, from which we can move forward and accomplish some positive result

So far, it would appear that TDCO is at -0.64, which should not be hard-starting - that is within oem factory specs - if ECT is above 180degF, PCM should not be callling for cold-advance of +12deg, unless ambient temps are below 50degf, which would throw IAT below 80degF, which would provoke PCM to call for cold-advance

What have you got for IAT?

IAT is 90
BTW I am not playing Mario Brothers, I am just providing all the information that I can. Temp outside is 35 degrees right now. My IAT is 90 because the truck has been idling for about an hour. The problem is I have been cramming all this info in the last two hours and I am just trying to keep it all straight. I have done nothing more than plug in the scanner and take some readings. Time set is now forgotten if it doesn't do any good.

Thanks for sticking with me.

Good - I'm the remote experience, you're my eyes and fingers - cool - ECT and IAT good, ambient temps low, PCM may stil be calling for some advance due to cold fuel temps, and PCM is using previous TDCO - OR - IP is out of position due to recent install, but PCM is still running on previous TDCO, which has not been relearned, and any subsequent TIME SET has resulted in PCM displaying actual new position of IP - either way, hard-start could result - could also be low ambients and low batteries, low-heat glowplugs, etc - but we need to address TDCO on the replacement IP

As you can see, there are several scenarios to account for while diagnosing a symptom resulted from an IP replacement - so, did the install tech do any IP timing after the replacement?

If you've read both the TDCO blurbs, you should know you are not to even think about
TIME SET, nor did I mention TIME SET - forget TIME SET - you need to do a scan, READ Desired and Actual timing and READ TDCO - FORGET TIME SET - TIME SET is not your friend in OBD2 - each time you do TIME SET, you're throwing things a little further off with that +12deg advance, which is not helping matters


I hope I'm being clear about that, because if you're doing Super Mario Bros on that keyboard as I'm trying to figger out what you have, we're taking two steps back for each no step forward - we're trying to establish a baseline, from which we can move forward and accomplish some positive result

So far, it would appear that TDCO is at -0.64, which should not be hard-starting - that is within oem factory specs - if ECT is above 180degF, PCM should not be callling for cold-advance of +12deg, unless ambient temps are below 50degf, which would throw IAT below 80degF, which would provoke PCM to call for cold-advance

What have you got for IAT?

I have nothin' to add to this thread mainly cuz I don't know jack about it, but that was funny right there!

This is why I have not put a wrench to it yet, or started twisting the IP, or giving the accelerator the one minute koeo push. After reading your TDCO post again, the forget the time set paragraph jumped right out at me (third time is a charm).

As I said in the beginning, I have good crank RPM, the glow plugs are good and operational, and I am in Illinois (COLD).

I was told that the dealer tech set the timing and TDCO when the IP was replaced.

So what's next?

Ok - I feel for ya - it's sunny 65deg here - so, shut the engine down, and perform the KOKO procedure - timing is important, so use your watch to time the intervals - and use the MT2500 in scan\observe mode, only - we just want to observe the results

I turned the truck off and waited 1 minute for PCM power down. Then I turned the key on, engine off then held accelerator down for 1 minute. I released throttle and then turned key off. Waited 30 seconds. Restarted and this is what I have;

IAT 95
desired timing 12
actual timing 11.8
TDCO -0.68

Not much of a change, but it appears to be moving in the right direction.

Question following this thead.
I thought the MT2500 couldn't set TDCO and Base time ?

Question following this thead.
I thought the MT2500 couldn't set TDCO and Base time ?

This thread explains the procedure and touches on the snap-on scanner thing.

http://dieselplace.com/forum/showthread.php?t=2599

Good - what we've established is that the IP is correctly timed mechanically, and PCM is aware of the change and has learned and is using current values for timing - now you'll need to adjust the IP, rotating towards the driver's-side ~2mm to a more advanced position, where PCM can reLEARN a new performance oriented TDCO value, ~-1.94deg - likely you're not interested in doing that tonite in 30deg weather, but that is the next step.

FYI - KOKO does TIME SET automatically, so there's no need of doing it with the scanner - where the scanner is a problem is that KOKO will only do it when conditions are permissive: 180deg ECT, 80deg IAT, no cold-advance, but the scanner can ignore that restriction, adding any cold-advance offset into the mix - PCM then may LEARN erronious value for TDCO - could even die and not restart, if the number is way outside probability - KOKO should always be used for OBD2 timing procedure in order to establish the baseline

So, what do you want do do now?

Thanks but I read that one and GMCTDs. I just still don't get it. TD said the MT2500 doesn't display the timing correctly but the values you were posting looked close to right . Only reason I asked was I'm still in the market for a scanner myself. My problem is I have both OBD1 and OBD2 so trying to find something that will do both(besides a 2000$ tech 2).

gmctd,

I might give it a shot here tonight, I will post after I try it to let you know where it ends up. Thanks for all of your help and patience.

acesneights,

I presume you are looking at used scanners. The snap-on one is pretty nice. If the numbers vary like TD says it will show that in the troubleshooter section in the scanner. If you are looking for more than a code reader, the mt2500 is a nice unit, as long as you don't need a lot of bi directional functions.

GMTDScan for OBD1 and Autoenginuity for OBD2 - both pcware scantools that coexist on your laptop, way much more user friendly than the Tech series, and, at 1/50th the price, much easier to acquire - ~125 for GMTDScan and ~250 for AE - can just barely buy a good code reader for that much - both pcware tools do all the TechX functions and commands, except reflash

The current MT2500 issue does read the correct values, but you still get short-changed on functionality - get the MT2500 for gassers (patooie!) - get TechX for 6.5TD functionality, or the easy-on-the-wallet pcware scantools

gmctd,

I might give it a shot here tonight, I will post after I try it to let you know where it ends up. Thanks for all of your help and patience.

Gonna have to fab up some wrenches to get the bolts loose. Hope to get it done tomorrow.

Can the TDC offset be set on the injecton pump, without removing the lower intake? Thanks