Two days in a row, the check engine light came on and all of a sudden it felt like I was driving through sand. Both times the check engine light went off after 1-2 minutes of driving, and power went back to normal.

Evoscan showed no DTC after the light turned off. (couldn't check while I was driving)

1st incident happened suddenly during cruising.

2nd incident started with a rough idle at a traffic light. Sounded like one cylinder was missing... when I gently reved the engine, it sounded like a Subaru, lol. Right after, the check engine light came on and power was down. At the next traffic light, idle sounded fine, but then it jumped to 2500 rpm suddenly and stayed there. Once I started moving, the light turned off, and the car went back to normal.

Any ideas? I think it may be a loose sensor connection, possibly the MAF.

Relevant notes: Tephra V7, 1000 cc injectors, running on 93 at the moment

 

i would suggest logging the car to see what is going on. do you have a wideband? how is the afr when this is happening. was the 100cc injectors recently installed?

 

I have a wideband installed. AFR looked fine during the incidents; it was holding about 14.8 during cruise and idle.

The injectors were installed a year ago. I've been running mostly E85, which I self-tuned for. The car actually runs better on E85; the idle is a bit rough on gasoline with the 1000 cc injectors.

Something else to note: both mornings this happened it was very cold (for Houston standards), about 25 degrees.

One other note: recently I've been having trouble uploading using ECU flash because of low battery voltage. I'm running a mini battery and it seems to be having some trouble with the cold. Don't know if this could be related or not.

 

Does sound like it battery related...check it first..

 

Could my problem be the FAA bit.10?

From the Tephra V7 page: FAA bit.10 disabled ("weird unknown" timing pull at cruise)

 

Use the Scan Tech proggi to read the "Pending codes"

These codes were stored in the ecu, so that temporary errors will be ready to read.

Evoscan only reads active codes, not the pending ones.

 

Check your TPS sensor....