My SE will start and idle, no problem. But just off idle, the rpms start jumping around. If I open the throttle just a little bit it will rev properly and then drop like it's about to die. It keeps doing this over and over. If I try to drive it, it jerks like if someone that can't drive a stick is driveing it.


Any Ideas?

Thanks,
Mike

 

That could be a bad Vent Solenoid Valve: https://www.rx7club.com/forum/showth...hlight=surging

But, for some reason, it sounds more like a bad or out of adjustment TPS to me: https://www.rx7club.com/forum/showth...&highlight=TPS

Either can cause idle "hunting/surging". Try TPS adjustment first - that's the cheapest. VSV is expensive, if you can find one. Mazda wants a couple hundred bucks for one

 

Thanks zookeeper,
I will try to adjust the tps tomorrow.

MIke

 

Mike... have you checked for possible vaccum leaks ? an easy way is to spray some carb cleaner around and if the engine starts surging.. then you've got a leak.. which would cause some idling issues

andy

 

Thanks, but my problem is not an idle problem. it idles perfect. From about 1300 rpms and above it starts trying to shut off. it's like if I where just sitting there jabing the throttle.

Mike

 

Hmm, intresting. Have you checked out the ignition system? Dizzy cap/rotor, plugs, wires, ignitors, ect? I've heard of dizzy caps deforming when cracked and causing misfires off idle...

Little info about the GSL-SE's computer. It gets it's tach signal from the trailing ignitor. IF this signal is lost for any reason (failed ignitor, or idiot owner moving the coil and not soldering the new wires onto the old harness ) the ECU thinks the car stalled and stops supplying fuel. (perfectly logical) Also, since it's the trigger for the fuel injection event, if there's no spark there's no fuel. I've had ignitors go in wierd ways, you might want to check out your ignitor(s). You may be getting weak triggering on leading (causing loss of power or misfire off idle, and the car won't rev very well at low RPM with only trailing) or weak triggering on trailing (causing loss of tach signal to the ECU causing fuel cutoff and loss of power and misfire ).

Out of curiosity... is it backfiring at all when it starts to misbehave? It's possible you've got leaky fuel injectors and are flooding, which would cause the car to hate it's life as well, tho I'd check out the ignition system first.

Good luck! Let us know what you find,
--matt

 

i like the tps 1st and then you need to start looking around.
put a timing light on it and make sure the l and t both are firing correctly. the ecu runs off of the trailing ignition so if the trailing ignition doesnt work the car wont run at all. you also might want to to check for a plugged air filter and maybe a clogged exhaust?
the other thing ive seen that is like your problem is a plugged fuel filter, ive had 2 aftermarket ones rust internally and plug up

mike

 

Thanks guys, All good info.



speckamp: Yes it does backfire. I thought that it did have leaking injectors when I first got it but now I'm starting to think otherwise. When I first got it It would not start when it got hot. this problem went away when I installed new plugs and a new air filter though.
The exhaust has a leak so I was assuming that this was the cause of the back fires.

As far as the ignition system. I know everything is good. The only thing I have not checked is the timing. I will do this tonight along with the TPS adjustment,


Thanks again,
Mike

 

Did you build the TPS adjusting harness? This is easy to do with a soldering gun, 2 light bulbs, and some wire and end clips. Once you get it built, I leave mine on the workbench and readjust whenever I think the car is 'stumbling' during steady-state driving conditions. Let me know if you want directions on how to build it. Worth the effort, HTH,

 

Found the problem. After running the test it turns out it was a bad TPS. I pulled the tps from the T2 intake I had and pluged it in. It worked perfect after a minor adjustment.
Thanks for all the help.
Thanks to Mike Thompson for doing most of the work.

Mike