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1998 Grand Marquis - stutters at WOT

The Check Engine light is on all the time and the following two symptoms occur:

  1. When its cold it takes a couple seconds of cranking longer to start than when its warm
  2. At wide open throttle it loses power and seems to stutter like its running out of gas. Again only when its cold. If the car has been run for a good 15 minutes or so it works fine at WOT.

I'm only assuming these are not normal since the Check Engine light is on. My questions are: has anyone else expeirienced this? And, secondly: assuming the ECU goes into closed loop at WOT does anyone know which sensors are or are'nt being used at WOT?

thanks, JCM900

Reply to
JCM900
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JCM900 opined in news:T9ydnX snipped-for-privacy@warpdrive.net:

have the codes read out.. that's what they are for... and WTH!!!! would you go to WOT before the engine warms up?

Reply to
Backyard Mechanic

No need to be rude now, I was just checking to see if someone else had the same problem before I drop $50 on a code scan. I would have thought that 10 minutes of driving down the highway would be enough to warm the engine up, but it still stutters till at least 15 minutes into the drive.

-JCM900

Reply to
JCM900

JCM900 opined in news: snipped-for-privacy@warpdrive.net:

well... if you explained it as you just did, i wouldnt have been rude.

i pictured you backing out of the drive and nailing it.

yes certainly 10 minutes on the highway is enough... more than enough. if you see the engine is slow to warm up on the gauge.. I'd question that

are you somewhere that parts stores dont offer free readout?

I'm sorta thinking ACT totally out or ECT off.. probably act cause ect usually acts the opposite.

here's something... disconnect the MAF harness; if it runs better, bingo...if it doesnt want to run at all, it's not the maf or act.

Reply to
Backyard Mechanic

Thanks! I'll try disconnecting the MAF tonight. After reading about the ACT it sure sounds like it could be the culprit. There will be an AutoZone opening soon in my area, and I've heard they do free scans. I'll have to check if Advance Auto or Checker Auto does them though as they already have stores open here.

-JCM900

Reply to
JCM900

Well, I got the codes read at Advance Auto. They came up with PO171 System Too Lean Bank 1 and PO174 System Too Lean Bank 2 When I disconnect the MAF the car is even more prone to stuttering or even dying completely when I give it any amount of gas.

-JCM900

Reply to
JCM900

two words......Fuel Filter......that is the best place to start...

Reply to
Scott M

I agree... if it idles okay after brief warmup and when warm, and doesnt stumble on mild accel, then it's likely fuel flow/capacity problem:

filter, FPReg, pump

Scott M opined in news:4ifZc.16122$ snipped-for-privacy@twister.socal.rr.com:

Reply to
Backyard Mechanic

Thanks guys! I'll look into those.

-JCM900

Reply to
JCM900

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