Chk Engine Light, Did I melt pistons or Burn up starter??


New Member
Jul 27, 2004
Replaced Calibration tube on MAF.. installed new spark plugs.... (after a cold start and alittle warming up..probably about 5-10mns) I set psi to 40. Timing was 12* Took it down the road about 2-3miles..

Later I checked over eveything and noticed a spark plug wasnt tightened enough.. doubled check them all.. Checked PSI and it was at 36psi.. I put it back at 40psi. After words the car seemed to start slower.. almost hesitating right before it cranks up..Ive had some problems with the battery draining it the past. I also recently tried to cleanup or make the ground connections better. But it only seemed different after I bumped the fuel back up. I Checked it again after another short drive and it was around 41psi. Have tried to maintain a .99 or lower TPS volt.

Im wondering if I might have burned the engine almost to the point of seizing from 36psi and 12*.. But for only less than 5 miles? Or if the starter/selenoid might be going out. Car beings normal first second during starting.. then slows down and starts up.. odd thing is the check light has now started to come on.. but the car runs way more stout that it did before the plugs..others were all fouled. I also recently reconnected the EGR valve to vacume..previously only elec. hooked up egr had no vacume.. Recently also installed amp and a 12" sub.. to rear mounted battery.. cranking amps of 750 or 720
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I do not see the rest of your combo but based upon just what's written in your post I would suggest the following: (in no particular order except for the very first one)

Pull the codes!!!!


1. Remove the starter and have it checked
2. Set your fuel pressure to stock or put your stock regulator back on and stop messin with it
3. Ensure that your balancer is true and that 12* is ACTUALLY 12*
4. Purchase a wideband 02 or take it to a dyno and get a good look at your Air/Fuel ratio (your meter/injector combo is probably out of whack)
5. Ensure that the functioning portions of your EGR setup is working correctly.
Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See for more descriptive help

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.
I got codes 31.. EVP sensor below min volt and 85.. Canister purge sol circuit mailfunction.. Well Im running a set of 40p heads/ e303/ TFS pistons/ 24lb/ street heat..

I didnt think that 12* 36psi is satisfactory..but is it lean enough to burn the engine after 5 miles?
Sitting here troubleshooting from my keyboard, I would say that it's a pretty safe bet that you've probably not done any permanent harm to pistons, rings, or valves.

You're did not mention running a blower or nitrous and haven't listed any unusually high compression rates so my guess is that you're probably good as far as that goes.

Now it's time for you to properly diagnose and fix the problem.

If you've convinced yourself that you've burned up pistons or some portion of the valve train, then a compression and leak down test will tell you for sure.
Well I was just unsure about the limits for psi.. I figured I was near the limit for safe lean conditions..I just wanted to get another opinion on whether or not I went beyond the limits and ran a high risk of engine damage.. I really think its got something to do with my starter or the electrical system.. cuz the car runs better than it has been..Im going to take it to a dyno this week hopefully.. I have another EGR im going to swap with and see if that does anything.

The car is NA.. nothing to add hp w/
are you sure you hooked the grounding strap back up from that connects from the back of the head to the firewall? Be sure and clean your grounds and connections real well. You can never have enough ground. I have a huge grounding strap on my GT...I need to take pictures.

I'm with Daggar...don't think you did any permanent damage. If it were running lean, I think your o2 sensors would catch a lean condition and the computer would start pulling timing back to compensate.

Stock fuel pressure is 38psi with the vacuum off of the regulator. Set it there and you'll probably be fine.