Power goes flat @ 4100

06-25-2002, 12:30 PM

About 6 months ago I noticed when I hit 4100 rpm the power abruptly drops off with occational misfire. Car starts fine, runs fine. Replaced O2 sensor, checked resistance on plug wires, and checked plug gap. Cap & rotor are slightly worn. 155 fuel pump about 5000 miles ago. Original injectors. No audible pinging.

Next planned steps are replacing ignition module, and coil. Any body have other recommendations? Should I continue on the ignition road or should I turn my attention to the fuel system? Could I be hitting valve float?

Thanks

sn95gt19 · 06-25-2002, 01:04 PM

MASS AIR SENSOR IS BAD, at least thats what mine was, and it did the same thing, does the car rev all the way out at part throttle? if so then i would change your mass air.

06-25-2002, 01:17 PM

Interesting idea. The problem does seem to be worse with the outside temp over 100, a bad mass air may help explain the change when the temp is high.

I think the revs are holding steady at part throttle, but I'll check.

How do you test the mass air meter?

sn95gt19 · 06-25-2002, 01:43 PM

i have no idea how to test one, but thats most likely it, i bought my 95gt for dirt cheap cause the dealership didnt know what was wrong with it (mass air) when you would floor it, the car wouldnt rev above 4000 rpms, i switched the mass air and the car moved out. i have had the same prob. with 3 of my mustangs and my buddy had one go bad on his 90lx, so i would say thats the culprit.

89lx
90lx
95gt
90gt
ALL HAVE HAD MASS AIRS GO BAD

PKRWUD · 06-25-2002, 03:09 PM

Could also be a clogged cat, but try swapping a known good maf in first.

Take care,
-Chris

jruppert · 06-26-2002, 12:19 AM

Well if you think its your Mass Air Meter then you should first check for codes. You might have something stored in your computer. Try taking your meter and turning it a 1/4 of a turn one way or the other. My guess your problem could be the TPS sensor. That sensor turns along with the throttle and at a certain point it might be picking up a bad reading and causing your computer to go nuts. I would test that and make sure the volt reading is right before replacing anything. Good Luck!

06-26-2002, 09:52 AM

Good suggestions.

I don't have anything to read codes with, but I can check the TPS. I played with it a couple of years ago and found no performance improvement so I set it back. I don't recall the correct voltage reading for it.

I may also try to find somebody with a good MAF and switch it out to see if it solves the problem.

06-25-2002, 12:30 PM	#1
5000Man Guest Posts: n/a	Power goes flat @ 4100 About 6 months ago I noticed when I hit 4100 rpm the power abruptly drops off with occational misfire. Car starts fine, runs fine. Replaced O2 sensor, checked resistance on plug wires, and checked plug gap. Cap & rotor are slightly worn. 155 fuel pump about 5000 miles ago. Original injectors. No audible pinging. Next planned steps are replacing ignition module, and coil. Any body have other recommendations? Should I continue on the ignition road or should I turn my attention to the fuel system? Could I be hitting valve float? Thanks

06-25-2002, 01:04 PM	#2
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	MASS AIR SENSOR IS BAD, at least thats what mine was, and it did the same thing, does the car rev all the way out at part throttle? if so then i would change your mass air. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

06-25-2002, 01:43 PM	#4
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	i have no idea how to test one, but thats most likely it, i bought my 95gt for dirt cheap cause the dealership didnt know what was wrong with it (mass air) when you would floor it, the car wouldnt rev above 4000 rpms, i switched the mass air and the car moved out. i have had the same prob. with 3 of my mustangs and my buddy had one go bad on his 90lx, so i would say thats the culprit. 89lx 90lx 95gt 90gt ALL HAVE HAD MASS AIRS GO BAD __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

06-25-2002, 03:09 PM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Could also be a clogged cat, but try swapping a known good maf in first. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
loss of power suddenly	jimdrechsler	Windsor Power	17	09-30-2004 08:49 PM
power for 500 hp daily	Torinalth	Power Adders	22	09-25-2003 11:54 PM
Power for the Power Amp	traderguy	Audio, Security, & Electronics	2	07-13-2003 08:07 PM
power shift?	JamGtStang	Windsor Power	6	03-01-2001 02:11 PM
Electrical power, where to splice?	Chris_H	Windsor Power	3	02-11-2001 08:29 PM

06-25-2002, 01:17 PM	#3
5000Man Guest Posts: n/a	Interesting idea. The problem does seem to be worse with the outside temp over 100, a bad mass air may help explain the change when the temp is high. I think the revs are holding steady at part throttle, but I'll check. How do you test the mass air meter?

06-26-2002, 12:19 AM	#6
jruppert Registered Member Join Date: Jul 2001 Location: Reed City Mi Posts: 106	Well if you think its your Mass Air Meter then you should first check for codes. You might have something stored in your computer. Try taking your meter and turning it a 1/4 of a turn one way or the other. My guess your problem could be the TPS sensor. That sensor turns along with the throttle and at a certain point it might be picking up a bad reading and causing your computer to go nuts. I would test that and make sure the volt reading is right before replacing anything. Good Luck!

06-26-2002, 09:52 AM	#7
5000Man Guest Posts: n/a	Good suggestions. I don't have anything to read codes with, but I can check the TPS. I played with it a couple of years ago and found no performance improvement so I set it back. I don't recall the correct voltage reading for it. I may also try to find somebody with a good MAF and switch it out to see if it solves the problem.