Hey all, Ive got a pretty wierd problem. Ive tried searching, but everything I came across I think I already tried. Anyways, whenever I drive in vacuum the car is fine, whenever in boost the car is fine. BUT, in the transition between vacuum and boost the car hesitates like a mofo. I am running a custom kit with the Hahn manifold + s16g @ 7psi. I am using a vortech FMU with stock injectors. I have a Trust E-Manage wired in for tuning. Im also using the screamin demon coil pack with MSD 8.5 wires and accell plugs gapped @ .060. I know thats a huge gap for a turbo car, but I tried gapping the plugs to about .035-.040 and the car almost didnt run. I dont think its a fuel issue, because Ive had the same setup for a long time and Ive never noticed a problem running too rich/lean (walbro 255hp, stock injectors). Im guessing its a MAP error, but Ive already tried replacing the Missing Link, using the Hahn FCD, using the E-Manage to put a voltage cap, etc. Ive even went as far as removing the MAP sensor wires out of the e-manage and running them directly to the ECU. Right now Im down to running the the car without any MAP bypass at all, and oddly that nearly solved the problem.

The MAP sensor is new, along with a new o2 sensor and a bunch of other things. Everything I could think of has already been redone... I would really appreciate any insight as to what to try next. Also, what do you guys suggest I gap my plugs at, because leaving them at .060 seems really bad to me.... Any help would be greatly appreciated. If you guys need any more info just post up and Ill get back to ya. Thanks!

Originally posted by neovbAlso, what do you guys suggest I gap my plugs at, because leaving them at .060 seems really bad to me....

You need to cut your spark plug gap in half. The N/A guys do not even run that wide of a gap. If you are boosting I would suggest starting at 0.030-0.035" range and go from there.

No suggestions regarding your MAP issue though, sorry.

Do you have a missing link? I have started quite a few threads about my problems with the missing link.

Have you tried the "DIY-Fuel Cut Defender"? The HRC one kind of sucks. I built the "DIY-Fuel Cut Defender" from parts found at Shit Shack and it works great. Here are a few of my old threads:

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=8&topic_id=75479&mesg_id=75479&listing_type=search
http://forums.2gnt.com/dcboard.php?az=show_topic&forum=26&topic_id=511&mesg_id=511&page=

No matter what plugs you have, if they're gapped at .060, you can't re-gap them to .030.

Throw away your plugs, buy NGK BKR7E plugs, (DO NOT BUY BKR7E-11) put them in gapped at .028-.030 which is how they should come out of the box.

Put a welding tip or other vacuum restrictor in the vacuum line for the FMU.

Throw away any blackbox-based Fuel Cut Defender or VCD. However, the Greddy E-manage seems to work really well as a MAP voltage clamp. Try changing the clamp voltage. It works better on 95's I think, they're less sensitive to MAP issues.

The missing link will hesitate slightly at transition. It's a mechanical check valve, so the point where the ball rolls into the opening isn't always perfect. Keep it clean and lubed with Marvel or other lightweight oil.

Originally posted by thedawg
No matter what plugs you have, if they're gapped at .060, you can't re-gap them to .030. Throw away your plugs, buy NGK BKR7E plugs, (DO NOT BUY BKR7E-11) put them in gapped at .028-.030 which is how they should come out of the box. Put a welding tip or other vacuum restrictor in the vacuum line for the FMU. Throw away any blackbox-based Fuel Cut Defender or VCD. However, the Greddy E-manage seems to work really well as a MAP voltage clamp. Try changing the clamp voltage. It works better on 95's I think, they're less sensitive to MAP issues. The missing link will hesitate slightly at transition. It's a mechanical check valve, so the point where the ball rolls into the opening isn't always perfect. Keep it clean and lubed with Marvel or other lightweight oil.

good advise.

Originally posted by thedawg
No matter what plugs you have, if they're gapped at .060, you can't re-gap them to .030.

gently tap them on a hard surface and the gap will close. then just use the gap tool to open to the gap you desire. if by hesitation you mean a missing sound, i would say it could be spark blowout due to the huge gap you have. I used to run one range hotter plugs with crane wires and the SD coil and it always misfired under 3k.

Originally posted by thedawg
No matter what plugs you have, if they're gapped at .060, you can't re-gap them to .030.

Originally posted by JWoodley gently tap them on a hard surface and the gap will close.

Read any manufacturer's website, they recommend that you never change the gap more than .008. If you get bkr7e-11's, you will have to close the gap .016-.030 which is 2-4x the allowable limit.

http://tinyurl.com/2pzgc

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=26&topic_id=342&mesg_id=342&page=#348

Good information! I hope you didnt take offense to that, I was just throwing out ideas. Keep up the good work. :thumbsup