batmanfc

My car has a strange shimmy or shake in 4th or 5th gear at any rpm under 2500. Would the wrong timing cause this? I'm not sure why it does this but it just doesn't want to accelerate and just shimmy under 2500 rpm. It doesn't lose any speed but doesn't gain any either. Not exactly sure why it is doing this. It idles high and fluctuates between 1300 to 1500 rpm. No vac leaks to cause the strange idle, so would that have something to do with it also?

rx-7 obsessed

year model ? any mod's ? anything done since this problem started. did u do anything prior to this issue like a mod that could create this problem...we need a little more info man

tIIsleeper

Get your hands on a timing light and find out!

Your idle problem seems tps related. Adjust the BAC or the set screw on the throttle body to get it down around 800. Adjust your tps and make sure it doesnt have any dead spots.

I dont get what you mean by shimmy or shake. Does this happen at all throttle positions? Do you hear any knock? Does the car boost at all? Seems like the knock sensor is retarding the timing severely when under high load.

batmanfc

Sorry I was tired when I posted it. It does have a full 3 inch turbo back and intake. Its an s5 motor. I have checked the timing once before and it was right but I'm not sure if it keeps going out of time. The have checked the tps and it is fine also. As far as the throttle positions go, it only does in under 2500 rpm at any throttle position unless just cruising, after that it doesn't do it at all no matter what the position of the throttle is in. There also is no knock. The car runs perfect after those rpms.

tIIsleeper

Try unplugging your map sensor then driving it

batmanfc

Where exactly is the map sensor? Is it the pressure sensor? If that fixes it while driving, does that mean it needs replacing?

tIIsleeper

Yes it is the pressure sensor, mounted on the passenger strut tower. So the car will accel through 2500 no problem until you try and get on the gas a little harder? Check for error codes. Unplugging the MAP sensor will send the ECU into open loop so it ignores some of the cars sensors. I honestly dont remember all of the sensors but if unplugging the map fixes it then something is up with one of them. Does it feel like fuel cut? Does the car vibrate more than usual when it occurs? Also once you get above 2500 is it an instant acceleration or is it gradual?

batmanfc

Ok I thought so but I was just checking. I will definetely give that a try. It accels fine until I try to give it more gas and then once I do the car starts to just vibrate but there is no miss or anything. It isn't anything like fuel cut and it isn't a surge of power or anything above 2500rpm but it does accelerate smoothly then and quite vibrating.

batmanfc

I did try disconnecting the pressure sensor, but it did not help at all.

HAILERS

Unplug the TPS and see how it goes. The TPS is shown in the FSM.

batmanfc

I'll try it. I know the tps is good and adjusted right because that was the first thing I tried haha. Would a bad tune cause it?