Power loss in once in closed loop

[TrueBlue95GT]

After my 88GT warms up and goes into closed loop mode, the car loses power in the higher rpms. When cold, it pulls all the way to redline, but when it goes into closed loop, it almost feels like weak spark in the higher rpms or valve float, but that doesnt make sense only when warm. It's definitely a computer control issue because I can turn the car off and turn it right back on and the problem goes away for a couple of minutes. I've changed the TFI module, distributor, spark plugs, wires, ignition coil, cap/rotor, oxygen sensors, and coolant temp sensor. Please help!!!!

 

[dragnazz5.0]

check for a vacuum leak....which would be less notirceable when warming up since the computer is running the car rich anyways.

 

[noslow1986]

thats odd i have the same problem i think im using a160 stat mine loses power at 4500 rpms almost feels likes a rev limiter

 

[HISSIN50]

FWIW, the car will go into closed loop within 30-120 seconds of start-up. Does it act up that quickly, or do you think it's an issue regarding an absolute engine temp or hot-strategy?

It'd be interesting to see what the TPS is reading when it acts up. Does it matter if you're accelerating hard or easy?

Good luck.

 

[dragnazz5.0]

i wouldnt think the system would go closed loop that quickly....ive seen newer cars take close to 5 minutes to hit closed loop....but thats just sitting there idling. but i could be wrong

 

[jrichker]

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

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 http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

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 http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

 

[TrueBlue95GT]

Checked the codes and nothing applicable... it takes a while to do it when its been sitting overnight, but when you turn it off and then back on while driving, it does it very quickly...you may get one run in on the quarter mile before it starts happening again. And yes, the only way you can tell is if you're WOT.

 

[TENGRAM]

Checked the codes and nothing applicable... it takes a while to do it when its been sitting overnight, but when you turn it off and then back on while driving, it does it very quickly...you may get one run in on the quarter mile before it starts happening again. And yes, the only way you can tell is if you're WOT.

WOT=open loop...

during WOT the only sensors the ECM utilizes are MAF (or map for pre89 cars) ECT, ACT, TPS, and VSS. do any of your codes refer to these? is your fuel supply system adequate? what gap do you have your plugs at? also worth mentioning is that when the ACT is cold at WOT it enriches fuel supply moreso than when ACT is warm.

out of curiosity, what codes did you get?