I just had this problem occur to me this week at the track. my second run i hit third gear and at about 4000-4500rpms, somewhere in there around 4100-4200 i'd guess, it stopped revving/pulling. not quite a rpm drop like the converter locking up but just a stoppage like a rev limiter

I have no rev limiter, and the converter is suppose to lock at 108mph and i now changed that to 118. It cant be the converter unless its now going bad which it shouldnt.

Sometimes the car does it, sometimes it doesnt. i ran around all day on some back roads trying to hit that point somewhere between 80-100mph or 4000-4500rpms or so. The car did it once while i was datalogging and i had no knock counts, blms looked to be 128 (newer stock replacement bosch nb o2) while it was stuck at that rpm, LV8 was up there around max of 208 or so, maf looked to be pulling in the right amount of air but i'll have to recheck that.

Is this the sign of bad fuel pressure regulator or bad fuel pump? or is it ignition related? the car ran sooo fine all year until these last two days. i dont know what to do.

 

Sort of sounds like it's running out of fuel. Like failing fuel pump.

If it was ignition or valve related, I'd expect it to happen in every gear. Of course, the same could be said of poor fuel delivery with EFI. . .

 

thats what i figured..it only happens in third gear. i hope its not a fuel pump, as i want to go to the track down in maryland next weekend and get it dyno tuned this next week as well.

i thought a bad fuel pump wouldnt have proper pressure at the fuel rails. Like it would be very unstable or drop off. my car holds fuel pressure just fine at idle and holds it for awhile once i turn the key off...

 

Short term pressure and long term flow are two different things. Not saying thats what it is (we're at the guessing game point) but it could be the problem. I had that problem on a carbed car of mine, the pump couldnt keep up to the demand but thats kind of a different issue.

 

i never had this problem before so it has to be the fuel pump or ignition at that point. I am planning on a cam next spring and will need a fuel pump anyway, so i think i may order one and get it here FAST so i can get it in and get to the track this upcoming weekend. I'll test the car out again come sunday and see how it goes.... i'm wanting to get it to the dyno this tuesday but i dont wanna waste time tuning ona possible bad pump. might as well upgrade..its probly dead...and its only 160 bucks with wiring harness from racetronixs...so might as well go for it and see what happens

 

OK update guys.... help me please

i have decided to check my 02 sensor milivolts and voltage at fuel pump. volts at fuel pump is fine, sitting at 13.60.

milivoltson the 02 however are not fine...atleast they dont look goodto me. dips realllylow sometimes down to like 80mv and then very high like 700-800mv, but not flucuating like it should from 200 to 600-700, or cross counting/switching. it was hovering at around 160-170mv for a bit then jumped around again. i never seen that before

BUT could a bad o2 sensor cause this upper rpm "revlimiter" problem? it sounded like it was fuel related. then again i'm not sure. does the 02's even have any input on WOT fueling? i didnt think they did.

this leads me to my next idea....could it be bad injectors causing the crazy 02readings? i wouldnt think so as the car runs fine at idle and part throttle and wot in all other gears.... nice and smooth like it has for the last 3-4 years

 

I may have a similar problem.

Did you find out what it was?

 

sorry i didnt update but yes! i had two bad fuel injectors...on number 1 cylinder and number 4 i believe it was. some reason it was running fine in first and second gears but was cuttin out in third

replaced the injectors and it now runs fine. Fuel pump was not the problem, neither was my ignition but it was good investment to upgrade anyway