drago86

When my 86 sport gets to about 5500 on full throttle it kinda hesitates, almost like a miss, it does it again at like 6500, could this be the infamous 3800 rpm hesitation, way late for some reason? it only does it at full throttle, and sometimes it doesnt do it at all. My spark plug wires are pretty new, the plugs are new (ngk trailing plugs are the way around, i think there all 8 or 9's but their a nice coco brown color, so i dont think this is the problem) i replaced the fuel filter not to long ago, maybe 6 months ago. it doesnt feel like it going lean to me though, maybe to rich, or somethign ignition

DoubleDown

My car does the exact same thing, and here is my guess:

Your engine has a exhaust pressure sensor that is fed by a tube of exhaust air coming from your cat. converter (or near by). Mazda designed the sensor to activate the second set of fuel injectors at around 3700 RPMs when the exhaust gas pressure passes a psi threashold. You can research this 3700rmp "hick-up" in the 2nd gen archives.

Either your sensor is not working correctly, so it takes more exhaust pressure to activiate it, or that you have a leak in the exhaust system that is delaying the pressure to reach the sesnor's threashold normally found at 3700 rpm.

IF SOMEONE KNOWS ELSE WISE, PLEASE LET ME KNOW. I don't profess to be an RX7 expert.

drago86

naw,.. the 3700 hesitation is cus of bad ecu grounds, and the 5th and 6th ports are operated offa exausht pressure in 86-88 NA's, what ive always happens at 5500, sometimes it just hesitates, others it kinda feels like its missing,.. i cant figure it out

Rotorific

iTrader: (1)

it is coming from your boost sensor that vacuum line that runs from your boost sensor to the engine where the upper and lower intake manifold meet, it has to do with that if you are not running the stock vacum tube with the pill in it then your car will not run properly thus you having a 5.5 -6.5k hesitation....it has happened to me too i just fixed it...

Thaniel

I would think it is the Vac line to the boost sensor as well. To check unplug the vac line from the boost sensor (or manifold) and take er for a spin. If the pill is gone it will run great with the line unplugged.

drago86

Thanks guys, your talking about the lil green pill that is on the line that comes of the solenoid with the blue wire connector that is closest to the front of the car right? i checked it and i replaced the vac lines on it with silicon ones, the pill i still there though. Does the pill stop working? am i even talking about the right one? i havent disconnected the line yet and taken it for a test drive, i will latter tonight however. Whats the lil pill control also?, thank you guys so much

dragondwc777

My car is doing the same thing I thought I was fuel cutting. Mine is like a cut out jerk pop at 5 to 6k rpms. I will check mine also. Thnx

drago86

HEY1, thank you guys so much!, its not the green thing, i searched the forum for boost pill and found out where it was, and sure enough, i had replaced the vac line, and no pill, so i spliced in a aquarium valve, turned down to be very very restrictive, works wonderfully now, thanks so much. we need to warn everyone who replaces their lines with silicon ones to skip the one that goes to the boost sensor. dragondwc, its the sensor on the pasenger side strut tower, it has one vac line on it that goes to the junction between the upper and lower manifold. just put anything in there that restricts it down to about a pinhole, and no more high rpm missing/ hesitating.

Thaniel

I made my "pill" by drilling a 1/16 hole in a piece of plastic and pushing that into the vac line.

DoubleDown

Is this Pill on turbo engines, non-turbo, or both?

RETed

High RPM miss can be the cause of an out-of-spec TPS.&nbsp Check WOT resistance not over 6.00k-ohms.



-Ted

dragondwc777

I fixed my car as well No green pill I had to make my own now my car seems to run fine Thnx I also checked my tps at wot it is about 7000, idle is about 1000 is this very bad?