03sport007

Over the weekend I installed some revshift motor mounts. All the research I did told me it would be a 2-4 hour job. I forgot to factor in the Maggie when I did my searches. I quickly figured out with the super charger installed I couldn’t raise the engine high enough to get the old mounts out. So I removed the exhaust manifolds. With the motor mounts and exhaust out of the way it was a perfect time to do spark plugs.

After getting everything back together I went for a drive and the car runs and feels good. New motor mounts make a big difference. I decide to have a little fun and notice if I go more than about 1/4 throttle the engine misses badly. It idles fine and if my wife was driving she’d never know there was an issue. Its only if you get on it a little. No issues before

I’m getting ready to re-check all the plugs, plug wires, etc but what really has me confused is the instant MPG readout. It’s very low. Normal driving its 4mpg whcih is usually about 15 . Coasting down a hill and the best I get is 9mpg normally closer to 40. This wouldn’t be affected by improperly installed plug wire? Anybody have any ideas?

BigBlock.Condor

The miss is likely spark related if nothing else was touched. Improperly gapped plugs or plug wires not snapped in all the way are both simple things to check before you start pulling your hair out.

Forcfed93

iTrader: (10)

The MPG readout factors on a lot of things, but in the case of a miss, you likely had to press the throttle much more than you would otherwise need to for the same effect, which uses more fuel and reduces the instant readout.

Interesting thing I found out of the instant MPG readout is that injector duty plays a major factor as well. Higher fuel pressure reduces the injector DC which increases MPG readout. Lower pressure raises injector DC which lowers the readout.

All the while, likely getting no better or worse MPG.

WRX_PWNER

Double check your gaps and make sure wires are on all the way. Pretty sure that's it.

07CTS-V

iTrader: (6)

O2 sensors?

Becker

iTrader: (4)

only thing u touched was exhaust and plugs and wires....I would look into the plugs, gaps, tightness, wires fully seated, resistance on the wires if they were new and o2 sensors and wiring.

03sport007

Thanks for the help. I'm coming from the FORD side so I'm a little behind the power curve. Logic says it should be something I took apart because everything was working great before. I ordered some AC Delco wires(Not cheap) and I'll start there. I'll pull the plugs again just to make sure. I would think with a bad O2 sensor connection it would throw a code. Maybe not? The Instant MPG being all jacked up is making me think its not the spark plugs/wires so I'm a little nervous. I did have the battery disconnected for three days but that shouldnt matter?



I've only had the car a month and it sucks not being able to drive it.

itsslow98

iTrader: (18)

Did you put the same type of plugs back in it? If you put stock plugs back in it that may be an issue with the maggie.

Naf

iTrader: (1)

Give your sparkplug wires a dose of wd40 and reinstall, check all your sensors are plugged in and also make sure you didnt unplug the egt by accident.

If it was fine before the MM then it should be fine after the mm...I feel you have a spark issue for you removed the headers...

Larry

iTrader: (4)

Did you install the plugs prior to the manifolds? Might have cracked one of the plugs installing the manifolds.

03sport007

Yes I did. That's a thought? Installing the manifolds by myself was no fun. I'm sure I read it somewhere but I loosely threaded some studs and hung the manifolds on those while I threaded the bolts and then replaced the studs once I got some bolts started. I went with tr6 spark plugs gapped at 40

I won't have a chance to work on it until this weekend. Thanks for ideas.

03sport007

This was it!!! Took all the plugs out and one was cracked. Never would have guessed that. Installed a new one with new plug wires and runs like a champ!! Thanks for the help!!!!!!!!!!!!!!!!!!

Larry

iTrader: (4)

Good deal! Glad you got it fixed!