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-   -   Borla Header install 89 YJ 4.2L, gasket question and Idle issue (

bdr3355 03-12-2012 07:27 AM

Borla Header install 89 YJ 4.2L, gasket question and Idle issue
Installed the Borla Header part # 17062 and a used intake manifold on my 1989 YJ 4.2L. Original Carter carb and all emissions intact. Two questions for anybody that is much better under the shade tree than I.

One: The Header came with a very thick gasket, do I need to install a second gasket for the intake which is like the factory setup?

Two: After installing the header I re-installed everything exactly as I found it, with the exception of the EGR tube which I couldn't remove from the stock header so I capped it off on both manifolds. Now when I start it the engine idles for about 2 seconds at 1k RPM and then runs up to 3k RPM for a couple seconds back down to 1k RPM and then dies. Can repeat this cycle if I hit the throttle after it returns to 1k. There is a lot of popping sounds also which further confuses me.

Any ideas? Guessing vacuum leak somewhere but this seems pretty extreme for a vacuum leak, right?

BDK 03-13-2012 12:03 AM

Sounds like you have a vacum leak and your timing is off.

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