MS2extra Engine Runs Poorly Intermittently

[ScottyB326]

Hey guys, I'm hoping to get some help with my MS2 issue. Occasionally the car runs really poorly, almost like the rev limiter is on, spitting and sputering, and lots of surging, but it kinda clears up 3500+ and sometimes it just runs great (most of the time). Idle is lower and more erratic when the problem is occuring, and it threatens to stall at stop lights. Running MS2extra 3.3.2, bone stock m20, and as bare bones as it gets: stock narrowband, stock afm iat sensor, stock clt sensor, disconnected the tps because no variable tps yet, and a tune that essentially replicates a stock ecu. Wiring is spliced into stock ECU wires so I could plug the ecu back in if this stuff didn't work.

When the problem is happening, the pulse width goes insane, all over from normal around 5 ms to over 25 ms at times. that's the only thing I've been able to notice.

Here's a section of data log when it happened:



Hopefully I've got semi enough info to get the message across, please let me know if there's other stuff I could include to help explain this confusing problem. I'm not so sure what I'm doing wrong, and if someone could please help I'd really appreciate it. I can explain the problem more but I'm assuming the data logs are more informative than me trying to explain it.....

Thanks in advanced!!

[ScottyB326]

Okay well sorry to waste everyone's forum space and time if you read through that, but I thought a little harder, and my tiny brain figured it out. So I set the accel enrichment to 100% map based (it had been 100% tps based) because I don't have a tps hooked up. I had always noticed the tps gauge on Tuner Studios would just freak out, anywhere from -1,600% tps to 2,500% tps (WTF!?!?) so I had closed the gauge out because it was annoying to look at. I noticed everytime my problem occured it was as soon as the tps sensor started flipping out. So now it's MAP based and boom problem solved!

Hopefully this is helpful to someone else cuz it almost left me stranded a few times!

[whodwho]

Careful If you don't have a TPS hooked up and don't have the TPS signal wire terminated with a resistor it will creep up you can trigger flood clear(above 70%) and not start

[ScottyB326]

The TPS signal creep is different than the gauge reading? The gauge reading doesn't creep, rather it fluctuates erratically across the range I mentioned.

Thus far I haven't had any problems starting it, and the variable TPS should be arriving in the next few days. I will also be installing the wideband, and getting rid of the afm box and wiring in the GM iat sensor I have.

I appreciate your advice though, and considering my circumstances, would you recommend I do that anyway for just the next few days?

[Jaxx_]

If you read the MS manual it says to run a 1000 ohm resistor across the TPS pins so it doesn't float above 0.

I run no TPS and you need this.

[Jaxx_]

Careful If you don't have a TPS hooked up and don't have the TPS signal wire terminated with a resistor it will creep up you can trigger flood clear(above 70%) and not start

this won't happen because when you cycle power to MS it will reset to 0%.

The alternative to having a resistor on the TPS is to set accel enrichment to 0% TPS, but it's a band-aid.

[ScottyB326]

Well I am running it 100% map acceleration enrichment and the car runs great.

Once I get the variable tps I can tune the car more the way I want it but for now it's running fantastic

[keyland]

The TPS signal creep is different than the gauge reading? The gauge reading doesn't creep, rather it fluctuates erratically across the range I mentioned.

Thus far I haven't had any problems starting it, and the variable TPS should be arriving in the next few days. I will also be installing the wideband, and getting rid of the afm box and wiring in the GM iat sensor I have.

I appreciate your advice though, and considering my circumstances, would you recommend I do that anyway for just the next few days?

The pull down resistor pretty much just makes sure the input stays at zero even when there's electrical noise.

As you already figured out, you can choose to disable flood clear and TPS enrich as a bandaid.

On my car I added the e36 TPS with the 3D printed spacer. I did swap a couple pins on the TPS plug as was recommended in another thread. The main reason for me was that I live on top of a large hill and I spend a lot of time rolling downhill in gear so I wanted fuel cut overrun.

[Jaxx_]

The pull down resistor pretty much just makes sure the input stays at zero even when there's electrical noise.

As you already figured out, you can choose to disable flood clear and TPS enrich as a bandaid.

On my car I added the e36 TPS with the 3D printed spacer. I did swap a couple pins on the TPS plug as was recommended in another thread. The main reason for me was that I live on top of a large hill and I spend a lot of time rolling downhill in gear so I wanted fuel cut overrun.

You can have fuel cut overrun without a TPS sensor.

I agree with disabling TPS EAE is a bandaid, and honestly I don't quite understand the big deal about throwing in a resistor across two pins in order to remove the issue... but each to their own.