Timing issues after head gasket replacement

[ariff]

So I have been driving the LC everyday since we successfully replaced the HG a few weeks ago. Everything seems great except for a bit of hesitation and power loss when cold off the line. I am thinking it may be due to timing. I tried setting it to 3 deg BTDC as the manual suggests. At that low the car will barely idle.. I don't remember this being an issue before the HG was replaced and I had set the timing. So I went to 6-7 degrees and it would stumble when going up a hill like no power. I then went to 10 degrees and this seems much better but still a little hesitation.. Going up to around 15 really seemed to help but I was a little scared to set it that high. Is it possible the valve job that was done on the head could cause the timing to need to be run hotter? Or could the distributor be off one tooth or something? When we first installed the distributor it was off and the car would not even run.. Anyone have any ideas what to check?
Thanks..

 

[baldilocks]

Is the rotor pointed at about 11 O’clock when number on pistion is at TDC on the firing stroke? Is the distributor lockdown bolt at about the mid point of the adjustment slot? That is how it should look when set to 3* with number 1 at TDC of the firing (power) stroke.

A lot of members seem to have difficulty setting the cams in properly too. You may need to revisit that step.

Vacuum leak???

 

[baldilocks]

 

[ariff]

I am pretty sure that is all as you described.. I'll double check everything over again.. I double checked and double checked the cams when installing here are some pics of my cams..

 

[ariff]

OK so went out and checked some things over here is what I found.. Here is a pic of the rotor at no 1 TDC compression stroke:

If I set the lock down bolt to the half way point and fire it up it runs right around 15 deg BTDC.. To get to 3 deg BTDC I have to rotate the dist all the way counter clockwise till the lock down bolt hits the dist housing.. So something is a bit off here. Any ideas? Maybe try installing the distributor again? Could it being one tooth off cause this kind of problem.. I hope it is not the dang ol cams.. Hate to have to tear into it again.. Also found a mystery coolant leak oh joy ;>( @BILT4ME, @2fpower , @half k cruiser any thoughts? Thanks everyone!

BTW ignore the FRAM filter I am running cheap oil and filter after the HG replacement.. After a few hundred miles I'll replace ;>)

 

[baldilocks]

The distributor is a tooth off but I doubt that’s the fix for your original gripe because you are still able to set the timing properly. It looks like your dizzy housing is clocked a bit more counter clockwise than the pic I posted.

When I bought my 80 the distributor was a tooth off but it ran well.

 

[BILT4ME]

This MAY answer your question. Pull the distributor, do the alignment thing, then reinsert and then check timing.

Then time it. Do you have your terminals bypassed with a paperclip? Yours is a 93 and this is from the 96 FSM, so there may be some variance on how, based on OBD1 VS OBD2.

 

[ariff]

Oh yeah those instructions are very familiar.. Thanks Mark

 

[BILT4ME]

Oh yeah those instructions are very familiar.. Thanks Mark

If your timing is still in spec, then I would be looking for a vacuum leak somewhere. Something missed or loose under the intake manifold perhaps?

"When cold off the line".... Did you have your injectors rebuilt?
Possible temp sensor issue? It has to be at operating temp to change voltage to the fuel pump and to change the fuel settings....or is that on only the OBD2 trucks?

 

[half k cruiser]

@ariff The pic of the cams looks right as long as you took that with #1 at TDC. Having the valves done is not going to change the timing needs. My money is that you are off by one tooth on the distributor. When you were re-installing it to the head with the VC off you should have been able to visually guide it in to the correct spot as there are marks to do so. If you put the VC back on it becomes more of a pain in the ass and its easy to misalign it. If it were me I would make certain my distributor was set proper, set the timing to 3* and see how it runs. If that doesn't fix it you can go further down the rabbit hole.

 

[ariff]

@ariff The pic of the cams looks right as long as you took that with #1 at TDC. Having the valves done is not going to change the timing needs. My money is that you are off by one tooth on the distributor. When you were re-installing it to the head with the VC off you should have been able to visually guide it in to the correct spot as there are marks to do so. If you put the VC back on it becomes more of a pain in the ass and its easy to misalign it. If it were me I would make certain my distributor was set proper, set the timing to 3* and see how it runs. If that doesn't fix it you can go further down the rabbit hole.

Yup that pic of the cams is no 1 at TDC.. I followed the service manual and they have you put on the vc before the distributor so I never installed it without the vc off.. Dang it.. I tried for a good 45 min to get the dist. installed properly following the service manual lining up the lines on the shaft and gear and it would go in where I thought it was correct, but it was always the same as when I started.. I marked it with a white dot.. Going one direction or the other it was obvious it was off as the rotor pointed to far ahead of number one or to far behind number one.. So Installed it where I thought it was correct lock down bolt in the middle and the rotor was pointing right at number one. I set the timing cold and everything worked great.. I got 3 deg btdc as per the manual and the lock down bolt was just a little past the middle. I set it to 7 deg BTDC and took it for a drive to get it up to temp. When I checked it again (pins jumped on the diag port) it was running at 15 BTDC.. So cold engine timing can be set per the service manual when it is warm I have the exact same issue.. runs great at around 15 deg when I try setting it to 3 deg the lockdown bolt bottoms out on the dist housing and the truck runs like crap.. Ideas?

 

[ppc]

When you jumper the diagnostic connector have you verified the CEL is flashing to confirm you are in base mode? If in base mode the timing should not change from cold to hot. Are you sure the timing light is setup and used properly? If all that is good then if the light is indicating the correct timing degree then the distributor is inserted properly, no one tooth off issues come into play. Have you removed the jumper when test driving? Have you pulled the EFI fuse or disconnected the battery to reset the ECM? The only other problem related to timing would be the cams not installed properly.

 

[whitey45]

What about the crank to cam timing? The timing chain!!

 

[ariff]

When you jumper the diagnostic connector have you verified the CEL is flashing to confirm you are in base mode? If in base mode the timing should not change from cold to hot. Are you sure the timing light is setup and used properly? If all that is good then if the light is indicating the correct timing degree then the distributor is inserted properly, no one tooth off issues come into play. Have you removed the jumper when test driving? Have you pulled the EFI fuse or disconnected the battery to reset the ECM? The only other problem related to timing would be the cams not installed properly.

Yes my CEL is flashing.. Timing light is setup properly on plug wire no 1 and positive to batt + and neg to batt neg. Assuming my timing light is working properly and not malfunctioning? Yes I remove the jumper when test driving. I had the battery disconnected when pulling the dist. for about 45 min or so.. So that should have reset the ECU.. After driving when warm I did check the timing with and without the jumper.. It was around 15 BTDC each time.. I then backed it down to around 10.. When putting the chain back on my match marks did line up.. So I am thinking that means the crank to cam timing is correct? Looks like I'll get to pull the vc this weekend ;<( bummer..

 

[BILT4ME]

Yes my CEL is flashing.. Timing light is setup properly on plug wire no 1 and positive to batt + and neg to batt neg. Assuming my timing light is working properly and not malfunctioning? Yes I remove the jumper when test driving. I had the battery disconnected when pulling the dist. for about 45 min or so.. So that should have reset the ECU.. After driving when warm I did check the timing with and without the jumper.. It was around 15 BTDC each time.. I then backed it down to around 10.. When putting the chain back on my match marks did line up.. So I am thinking that means the crank to cam timing is correct? Looks like I'll get to pull the vc this weekend ;<( bummer..

Your crank to cam timing is correct if you set the cams at TDC on #1 compression stroke.

 

[ariff]

Your crank to cam timing is correct if you set the cams at TDC on #1 compression stroke.

Yes I sure did.. The thing is the car runs great at 15 btdc no pinging no hesitation.. I am just scratching my head why it runs like crap at 3 deg btdc.. Seems like a distributor not installed properly issue but it sure appears to be in there correctly.. And the whole cold vs warm timing difference with TE1 and E1 shorted is strange.. Cold engine times perfectly? Ughh losing hair ;>) The only other thing I can think of is I did replace the ecm with one from a 94. I guess there could be something wrong with it?

 

[BILT4ME]

Yes I sure did.. The thing is the car runs great at 15 btdc no pinging no hesitation.. I am just scratching my head why it runs like crap at 3 deg btdc.. Seems like a distributor not installed properly issue but it sure appears to be in there correctly.. And the whole cold vs warm timing difference with TE1 and E1 shorted is strange.. Cold engine times perfectly? Ughh losing hair ;>) The only other thing I can think of is I did replace the ecm with one from a 94. I guess there could be something wrong with it?

What about the IAC valve? Could it NOT be a TIMING issue, but a FUELING issue after the truck reaches operating temp and then it wants to die? That could be the Idle Air Control or whatever the fuel pump uses to step up into closed loop?

I always get this confused. Maybe @scottryana can advise on this part. I think he has dealt with it. A 93 with fresh HG replacement.

 

[ariff]

Not sure.. it never really wants to die.. Just seems sluggish. Still seems like a timing issue since I can make the problem go away by setting to around 15 btdc..

 

[baldilocks]

Advancing timing can mask a vacuum leak.
When the crank was set too “TDC”, are you sure you aligned the mark on the crank with the zero mark on the timing chain cover? If you are sure of this, then it’s beginnihg to look like a vacuum leak somewhere.

 

[ariff]

Advancing timing can mask a vacuum leak.
When the crank was set too “TDC”, are you sure you aligned the mark on the crank with the zero mark on the timing chain cover? If you are sure of this, then it’s beginnihg to look like a vacuum leak somewhere.

Yup I triple checked all that.. I did replace all vacuum hoses and also removed the EGR and Pair valve.. I removed those vsv's as well so they are no longer under the intake. I'll take a look at vacuum leaks as well..