1992 Chevy Blazer Engine lopes

BADWRENCH

MEMBER
1992 CHEVROLET BLAZER

Engine Performance problem
1992 Chevy Blazer 6 cyl Four Wheel Drive Automatic

92 Blazer 4.3 CPI.
Replaced eng. After timing adjustment engine ran fine. On the second test run the engine died just as I was turning into my drive way. Now when I start the engine sound like it has a big cam in it as it lopes.
I have checked for vacuum leaks by spraying carb. Cleaner around the intake--no change. I pulled and cleaned the IAC. I have not done the ohms check of the IAC--will do today.

One thing I did notice is if you remove the hose from the brake booster the loping stops but the Fidel is some what high.

What type vacuum reading should I have from the intake port on the rear of intake?
thanks for any help.

3 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok lets check a couple of things first ok. Now you said if you unplug the brake booster it stops have you pluged the end of the vacuum line off to see what happens then? If the idle stops surging then it may be a bad booster. How old it the cap, rotor and plugs? I never assume that some one puts in a new engine and replaces these. What is the fuel pressure doing? Get back to me with some info and we will go from there. Oh yea the engine a new rebuilt or a salvage yard engine?

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Tuesday, November 11th, 2008 AT 10:42 AM

BADWRENCH

MEMBER
4 POSTS

Thanks for reply. I cleaned the IAC valve one more time and that seems to have fixed it.
FYI: The engine was a rebuilt one.

Can u help with the following
1. I do not get a check eng light at all. A code reader shows signal when plugged in. Hate to have to pull dash apart. What is wire color from ECM for the light? I may just put a external light.

2. When I put the timing chain cover on I made sure the dots on the cam and crank gears were aligned properly. Then when I put the dampener on neither of the two factory marks aligned with scale. If I recall I think the second one should be used. At any rate I just put a mark on the dampener at the 0 degree indicator. My mark is to the right of the two factory lines. After the engine was warm I shut off, unplugged the wire under the glove box and adjusted my timing to 0 degrees using my mark. After hooking the wire back up it seem to run ok.

Does this sound ok?

Thanks for any help.

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Wednesday, November 12th, 2008 AT 7:42 AM

RACEFAN966

MECHANIC
5,029 POSTS

Yes this sound right it sounds like you put everything back as it should be great job. As for the wire color here a wiring diagram of the instrument cluster and the engine light diagram is on it hope this helps. Let me know how it goes ok. You may need to save pic and then make it bigger so you pan it and be able to read it too. ok.