1999 Chevy Blazer 4.3

[black86glhs]

Have a friend with this truck. Engine was just rebuilt. Starts and runs fine. Light throttle is good, but anything over 1/4 throttle and it is gutless. Does not miss, hesitate or stutter in any way. No codes. Drives exactly the same with the exhaust cracked open before the cat as it does with no exhaust leaks. Feels like a 2.2/2.5 with the timing belt off a tooth. No power all the way to 5500RPM.
There is the back story. My guess is one of 2 things. Either the distributor timing is off or the cam timing is off. Even though there is no timing adjustment at the distributor like a normal small block, it is possible to be off a tooth when installing, I think?
Also, verified map and maf are working and no vacuum leaks.
Anyone got any ideas or thoughts........other than sell it or buy a Dodge....LOL.

Thanks.

[bradp]

Fuel pressure....water in the fuel tank...just for $hits and giggles unplug the MAF and see how it runs.

[black86glhs]

Fuel pressure good, +60 psi. Fuel is also good. Not sure if he unplugged the MAF yet. I'll check on that. MAF was changing on the scanner, but worth looking at. Thanks.

[turbovanman²]

Yes, you can still get the dizzy installed wrong, I bet he's a tooth out. Set at TDC, there is an arrow on the dizzy which you align the rotor.

[black86glhs]

Yes, you can still get the dizzy installed wrong, I bet he's a tooth out. Set at TDC, there is an arrow on the dizzy which you align the rotor.

Ok, that is what I thought. He said he will check it. Thanks.

[black86glhs]

He is going to perform a compression test next. The timing marks lined up. It just doesn't make any power. No misfires or cutting out, just no nuts to it.

[bradp]

He is going to perform a compression test next. The timing marks lined up. It just doesn't make any power. No misfires or cutting out, just no nuts to it.

Did the rockers get over-tightened?

[turbovanman²]

That sucks, hmmmmmmm, wonder if he got the timing chain on wrong?

Brad, rockers aren't adjustable, IIRC.

[black86glhs]

Did the rockers get over-tightened?

I tried to get him to usee the 2001+ heads but his rebuilder told him they weren't the right ones for his. They will bolt up and work fine, but head followed the guys advice. The guy who built it is more into diesels, so he didn't know. So he might have them torqued down.

That sucks, hmmmmmmm, wonder if he got the timing chain on wrong?

Brad, rockers aren't adjustable, IIRC.

That is what we were thinking. Like said above, I'm not sure if he did it or if the machine shop did it. I'll check with him later. This is going to be something really stupid, I can tell already...lol. Thanks guys.

[turbovanman²]

What heads is he running? The Vortec heads are all the same from 96+, there is no different head for 2001+ engines?

[black86glhs]

What heads is he running? The Vortec heads are all the same from 96+, there is no different head for 2001+ engines?

The heads and valvetrain changed around 2000-2001. Believe me, I have already been thru this.

[turbovanman²]

The heads and valvetrain changed around 2000-2001. Believe me, I have already been thru this.

From all I've seen, nope. What changes?

Not sure what you were working on but part number is the same on the head from 96-2005. I've worked on lots and never noticed a thing. The earlier ones had head changes and valve train changes, some were adjustable, some weren't etc.

http://www.gmpartsdepartment.com/par...el=S15%20jimmy

1998 GMC S15 jimmy



Description Year MSRP Price Core Price Your Price
cylinder head, s-series - 2.2l - 2.2L 1998 $796.93 $0.00 $641.53
Engine - cylinder head & valves - cylinder head
View Illustration
cylinder head, s-series - 4.3l w/balance shaft - 4.3L W/BALANCE SHAFT 96-05 $672.13 $0.00 $440.58
Engine - cylinder head & valves - cylinder head
View Illustration

[Orangetona]

Possible EGR problem? I know 4.3Ls had some EGR issues. Or a weak coil.

[black86glhs]

From all I've seen, nope. What changes?

Not sure what you were working on but part number is the same on the head from 96-2005. I've worked on lots and never noticed a thing. The earlier ones had head changes and valve train changes, some were adjustable, some weren't etc.

http://www.gmpartsdepartment.com/par...el=S15%20jimmy

Ok....I'll say this slower.....I.....have ....already.....been......thru.......this. The Valve train was different. Also, the intake ports were a little different. I can't find the article I read back when I was finding cyl heads for this truck. The previous owner cracked both of them. Like I said, they will work as long as you swap the valve train over.

[bradp]

Possible EGR problem? I know 4.3Ls had some EGR issues. Or a weak coil.

Weak coil sounds like a possibility.

[black86glhs]

He swapped the coil, ign module, crank sensor(previous issue), MAF and TPS over to his 96 and it ran flawlessly.

[Orangetona]

Sounds like its time for a dodge lol

[black86glhs]

Sounds like its time for a dodge lol

Yeah, I'm starting to think the same. lol

[turbovanman²]

Ok....I'll say this slower.....I.....have ....already.....been......thru.......this. The Valve train was different. Also, the intake ports were a little different. I can't find the article I read back when I was finding cyl heads for this truck. The previous owner cracked both of them. Like I said, they will work as long as you swap the valve train over.

WHAT!!!!!!!!!!!

And I'll say again, I've worked on both and NEVER noticed any difference. I'll phone my friend at GM to get part numbers.

Your thinking of the the 3100 or 3.8's, they changed valve train etc.


Ok, so technically, we are both right, damn GM.

The part number for the heads is the same for both years, BUT the valve train lists differently for the 98 vs 01, AND to make it worse, if you order a head from GM, even though the part number is the same, you have to order or use the 01 valve train.

So I sorta apologize,

[black86glhs]

Considering I'm the one who took the heads of the 2001 and compared them to the 1999 heads, I know what I was looking at. The studs changed along with roller rockers. I also read some change to the intake port, but can't verify that.
I had not seen it before either. But found out the hard way. Now I have a set of 2001 heads in the garage and no 4.3 to install them on.