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Discussion Starter · #1 ·
Hello guys.
First, sorry for my english, not my native language.

First post for me.
Chevy Tahoe 1994 6.5 i rebuilt engine but I'm not able to find right position of injection diesel pump because previous ovner it move optical sensor and, with engine rebuild, it start but smoke and generate error 88 and 34.
I have pc program type ScanTech and cable can read codes and able to set.
I'm not able to understand why, if I move left or right the injection pump, value of 'Actual timing pump' doesn't change (always at 25,5), of course engine smoke crazy (grey) and use a lot of diesel.
Sometimes, when I change pump position, start smoke black and crazy.
My intention, for tomorrow, is to put sensor on previous position (passenger side), make a mark and test with program til l find something change.

Can someone tell me how to made more faster procedure or give me suggestions how to find proper position?
This problem make me crazy!
Transport truck to the garage of mechanic is something i will try don't do.
Thanks in advance to everyone.
 

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Hello, I am dealing with a similar situation as yours, rebuilt the engine and injection pump timing is way off it appears... I can say from my experience so far that without a way to see what TDC timing is its very painful. I see you have the Tech 2 SW clone so you can do all of the necessary steps to Set TDC and TDC offset for the pump. Once you get engine above 170 do the Command Time Set from the Tech 2, it will show you the desired timing at zero and actual will change from the high number you're seeing to whatever the TDC is. If the engine quits your base timing is too advanced. Before you do the command time set, and engine is hot access the 3 nuts that hold it in place and you can set it with only one tight when you make your adjustments. Once you get it set then you can tighten all 3.

You need a tool to move the IP and I found a ratcheting end wrench will get to all 3 bolts. Not easy but possible. You might have to take off the serpt belt and move the Ac out of the way for one of the bolts depending on the year of your truck. Before you loosen them make a reference mark on the aluminum bracket that holds the pump and make this line go onto the Inj pump. Then you have a starting point to determine roughly where it was before you adjust it, and secondly it helps you see how much movement you are making to the passenger side or the driver side when you rotate the pump with the injection pump wrench. The FAQ even has a doc on the dimensions on how to build an inj pump wrench or you can buy one.

I have learned by trial and error a good starting point is when the fuel shut off solenoid valve on the injection pump is level you are very close to the TDC value of -3.5 deg. If you have to move it use the inj pump wrench and if its close you can move the pump with the top nut still snug. Once you get the TDC Time set correctly you can force the TDC offset from the Tech 2. It's another menu on the tool if you go back one step on the injection pump menu. You can command the TDC offset several times and you don;t have to to the Key On Key Off method, or at least I didn't with the Tech 2.

Take a look at the FAQ for the Injection pump and google for the Tech 2 manual it helps as there is no one who has really published the steps that I could find. I found a manual and it helpd me understand the functions and what menu I needed to be in to get to the Time set function. There's a ton you can do with it. I hope you get it working.. I will post my results when I get mine resolved as we are experiencing similar issues and I think mine now involves moving the timing gear one way or another due to the readings I see after I got everything set correctly with the Time set for TDC and the TDC offset.


Good luck and I hope you get it fixed
 
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Discussion Starter · #6 ·
Ciao, ho a che fare con una situazione simile alla tua, la fasatura del motore e della pompa di iniezione ricostruita è lontana, sembra ... Posso dire dalla mia esperienza finora che senza un modo per vedere quale fasatura PMS è molto doloroso. Vedo che hai il clone SW Tech 2 in modo da poter eseguire tutti i passaggi necessari per impostare l'offset TDC e TDC per la pompa. Una volta ottenuto il motore sopra 170, esegui il Command Time Set dal Tech 2, ti mostrerà il tempo desiderato a zero e l'effettivo cambierà dal numero alto che stai vedendo a qualunque sia il TDC. Se il motore si spegne, la tempistica di base è troppo avanzata. Prima di eseguire il tempo di comando impostato, e il motore è caldo, accedere ai 3 dadi che lo tengono in posizione e puoi impostarlo con una sola stretta quando esegui le regolazioni. Una volta impostato, puoi stringere tutti e 3.

Hai bisogno di uno strumento per spostare l'IP e ho scoperto che una chiave a cricchetto raggiungerà tutti e 3 i bulloni. Non facile ma possibile. Potrebbe essere necessario togliere la cintura del serpente e spostare l'Ac per uno dei bulloni a seconda dell'anno del tuo camion. Prima di allentarli, fare un segno di riferimento sulla staffa in alluminio che sostiene la pompa e fare in modo che questa linea vada sulla pompa Inj. Quindi hai un punto di partenza per determinare approssimativamente dove si trovava prima di regolarlo, e in secondo luogo ti aiuta a vedere quanto movimento stai facendo sul lato passeggero o sul lato guida quando ruoti la pompa con la chiave della pompa di iniezione. Le FAQ hanno anche un documento sulle dimensioni su come costruire una chiave per pompa inj o puoi acquistarne una.

Ho imparato per tentativi ed errori che un buon punto di partenza è quando l'elettrovalvola di intercettazione del carburante sulla pompa di iniezione è a livello, sei molto vicino al valore TDC di -3,5 gradi. Se devi spostarla usa la chiave per pompa inj e se è chiusa puoi spostare la pompa con il dado superiore ancora aderente. Dopo aver impostato correttamente l'ora TDC, è possibile forzare l'offset TDC dal Tech 2. È un altro menu dello strumento se si torna indietro di un passaggio nel menu della pompa di iniezione. Puoi comandare l'offset TDC più volte e non devi utilizzare il metodo Key On Key Off, o almeno non l'ho fatto con Tech 2.

Dai un'occhiata alle FAQ per la pompa di iniezione e google per il manuale Tech 2 aiuta in quanto non c'è nessuno che abbia davvero pubblicato i passaggi che sono riuscito a trovare. Ho trovato un manuale che mi ha aiutato a capire le funzioni e in quale menu dovevo trovarmi per accedere alla funzione di impostazione dell'ora. C'è un sacco che puoi fare con esso. Spero che tu lo faccia funzionare .. Pubblicherò i miei risultati quando avrò risolto i miei poiché stiamo riscontrando problemi simili e penso che il mio ora comporti lo spostamento dell'ingranaggio della distribuzione in un modo o nell'altro a causa delle letture che vedo dopo aver impostato tutto correttamente con il tempo impostato per TDC e l'offset TDC.


Buona fortuna e spero che tu lo risolva
[/CITAZIONE]
Yesterday I remove water pump because on computer I always read "actual timing" 25.5 (not able to change it, or 25.5 or zero 0,doesn't matter which ppsition was the pump) and thinking I assemble wrong the gear of injection pump but i discover marks are in a right position.
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Next week, maybe am lucky, i change entire pcm or only chip because also i discover memory is corrupted (workshop manual is clear about TDC, problem can be by wrong tdc or memory broken/corrupted).
Otherwise, I think pnly chance is to towing truck to workshop.
I will upgrade me to and thank you for your suggestions.
 

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Very interesting.. It seems the cam and pump might be off in your situation but I am no expert for sure! : ). Good luck I hope you get it working. With mine the actual injection timing will decrease to 3.5 deg when I turn on the time set command. That's what is so puzzling to me with this pump. The TDC is at spec setting, the TDC offset is withing spec settings, the actual vs desired seemed high to me but others in the post show similar numbers. The truck will start with Optical Sensor unplugged or the crank sensor unplugged so it appears both are ok?

I am going to test it today and check the fuel flow rate at idle to see what it is when temps are above 170. From some posts I've read its supposed to be between 7mm and 10mm of fuel. Also read the pulse rate should be below 2? Mine was at 1.88 at one time but its higher last time I tested it. I have a small leak as well I need to locate, I suspect one of my inj lines is leaking due to all of the back and forth adjusting I've done to this pump. When I first started the engine after re-build I had one dripping.
 
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Hello, wanted to share some information on the injection pump and my findings today. I had purchased a new Standadyne optical sensor, but due to timing issues felt it might be adding to the issues so I re-installed the old one. Fought the timing on the pump, bought a Tech 2 clone hand held and worked on my TDC set and TDC offset until they were correct. Truck still started terribly and wasn't smooth at idle. Today I re-installed the new optical sensor and placed it in the same basic position as the old one. Truck loped terribly. Moved it toward the passenger side, some improvement but I noticed the fuel flow rate was erratic, bouncing between 2 and unreliable. I figured I went too far and truck was in limp mode, so I barely moved it back towards the driver's side and idle improved and fuel flow was now 5mm3. I adjusted it again and got it to 7 with a slight bounce to 6 once in awhile and it started beautifully. Idle was smooth, high idle was smooth, blipping the throttle was crisp and responsive. All this time I never got any Check Engine Light codes or any faults. Timing stayed the same, TDC offset changed somehow to -1.85 with the base a5 -3.5..

So if your pump is acting up with the timing in spec, double check the fuel flow at idle when at temps above 170 or close to it. If its not between 7 and 10mm you need to adjust the optical sensor and or replace based on what I've experienced. I have noticed the desired vs actual timing decreased from 16.1 to 15.1 for some reason as well.. Very odd but it seems like the IP is working.

I need to give it some road time to see how it really behaves but this has made a big difference. The truck still has some vibrations I'm not used to @ 2K rpm but that might be the poly mounts I installed. The old rubber ones were shot and I suspect the new harder motor mounts might be the causue for the added vibrations or the new plastic fan blades on the fan clutch, just a hunch as it smooths out about 2200 rpm.
 

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Hi was your harmonic balancer replaced
 
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I was having some issues with my 94 Blazer after an injection pump replacement recently. I performed a TDCO with the pump too far advanced and it set a code 88. There is a learning curve with these with Time Set and TDCO and it’s a little confusing at first as I found. I now have a much greater understanding! Anyway, the code 88 set as a hard code and TDCO was -2.02. If I cleared the code with GMTDscan Tech it would come right back with the ignition on, but not running or cranking. Reading previous threads I found one where OkDually said the ECM needed to be replaced at this point which made sense since if you can’t clear the codes, you can’t run another TDCO. I bought an ACDelco reman ECM and was able to get it running great again.
 

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I was having some issues with my 94 Blazer after an injection pump replacement recently. I performed a TDCO with the pump too far advanced and it set a code 88. There is a learning curve with these with Time Set and TDCO and it’s a little confusing at first as I found. I now have a much greater understanding! Anyway, the code 88 set as a hard code and TDCO was -2.02. If I cleared the code with GMTDscan Tech it would come right back with the ignition on, but not running or cranking. Reading previous threads I found one where OkDually said the ECM needed to be replaced at this point which made sense since if you can’t clear the codes, you can’t run another TDCO. I bought an ACDelco reman ECM and was able to get it running great again.

Thanks for the information. Glad you got it running.

Mac
 

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I was having some issues with my 94 Blazer after an injection pump replacement recently. I performed a TDCO with the pump too far advanced and it set a code 88. There is a learning curve with these with Time Set and TDCO and it’s a little confusing at first as I found. I now have a much greater understanding! Anyway, the code 88 set as a hard code and TDCO was -2.02. If I cleared the code with GMTDscan Tech it would come right back with the ignition on, but not running or cranking. Reading previous threads I found one where OkDually said the ECM needed to be replaced at this point which made sense since if you can’t clear the codes, you can’t run another TDCO. I bought an ACDelco reman ECM and was able to get it running great again.
Interesting fact about the ECM. I guess where the data is stored in EEprom you get 10K writes or something like that before the chipset is done accepting re-writes? Good to know, back in 94 chipsets and the tech was pretty limited so it makes sense but is unfortunate. I wonder if you can just get a new prom burned and have a good spare?
 

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I reused the eprom because it was an expensive Heath chip that came in the truck when I bought it. I believe they are read only in obd1. Something in the ECM itself was causing the issue. You can buy spare obd1 EPROMs, but I’ve never had to replace one in any vehicle I’ve owned.
 

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Discussion Starter · #15 ·
PerToday i got a used ECM because there are many errors (memory dump corrupted!) and is clearly write on shop manual TDC error can be created only by wrong position pump or memory damaged.
Tomorrow I put back water pump and test again the truck.
Cross the funger for me 😢.
 

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If I were you, I would set the injection pump so the fuel shut-off solenoid is level and the timing cover studs are centered in the ears/adjustment slots of the injection pump. Run it and do the Time Set and make sure the base timing is very close to the recommended 3.5 degrees. If not, adjust the pump and do Time Set until it is. Only then would I attempt a TDCO. You don’t want the ECM to get “stuck” with codes like the old one, especially the killer code 88. Since it’s a used ECM, it might have a good TDCO programmed into it and you could just leave it.
 

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Discussion Starter · #17 ·
If I were you, I would set the injection pump so the fuel shut-off solenoid is level and the timing cover studs are centered in the ears/adjustment slots of the injection pump. Run it and do the Time Set and make sure the base timing is very close to the recommended 3.5 degrees. If not, adjust the pump and do Time Set until it is. Only then would I attempt a TDCO. You don’t want the ECM to get “stuck” with codes like the old one, especially the killer code 88. Since it’s a used ECM, it might have a good TDCO programmed into it and you could just leave it.
Today I reassemble water pump but first test ECM with computer GMTDScantech about memory error if there are still problem with this.
I will post my results tonight.
I cross finger on my feet, not only on my hands😂
 

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Discussion Starter · #18 · (Edited)
Results of today:
I understand I doing something wrong but WHERE???!!?!?
Injection gear pump is on right position but am not able to change this 25.5.
Or 0 or 25.5.
I try late next week with fresh mind and lookinf for it.
If 9someone have suggestions, is welcome!
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Wait, you said in the original post that you had a code 34. You should check your stepper motor and make sure it is working. Have someone rev the engine while you watch the stepper motor and make sure it is moving. They get stuck sometimes. A code 34 could be related to timing being off, but it could also be a stepper motor problem.
 

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Discussion Starter · #20 · (Edited)
Wait, you said in the original post that you had a code 34. You should check your stepper motor and make sure it is working. Have someone rev the engine while you watch the stepper motor and make sure it is moving. They get stuck sometimes. A code 34 could be related to timing being off, but it could also be a stepper motor problem.
No more errors 9x cylinder fault but still error 34 (not every test) and error 88.
Doesn't matter which position is injection pump, am not able to change or adjust from 25.5. Always 25.5 or 0.
I forgot: stepper motor is new.
Previous was broken.
 
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