9psi CTSC idle and throttle issues

I'm having the following issues with my 9psi CTSC on my 1992 NSX (running with CT intake, headers, exhaust, upgraded injectors and fuel pump):

- sometimes unstable idle
- sometimes throttle oscillates when moving from acceleration to constant throttle around 70-90mph

I'm running an AEM FIC piggyback and Shad suggested the later may be due to the piggyback fighting with the OEM ECU.

Anyone else experienced these? If so, any advice on fixing them?

Would moving to a standalone EMS help?
If so, which one is recommended?

Could the throttle issue be SC belt slipping? The belt seems to be tight on inspection but I've read it can still slip.

Have you cleaned the throttle body and idle air passages? Have you inspected the bypass hose for cracks?

Can you explain this more?
" sometimes throttle oscillates when moving from acceleration to constant throttle around 70-90mph"

Your car is a 92 which has cable/manual throttle. The ECU has no control over throttle the way it seems you're describing. The ECU can only add more fuel or adjust timing. It cannot add more air explicitly. The way air can enter the system is via a vacuum leak or possibly a faulty Idle Air Control Valve. You might want to clean that or check if it's faulty.

As Jason said, a cracked bypass hose would cause a vacuum leak.

Hey jwmelvin & Ryu, thanks for the responses.

Sorry for the confusion, when I say "throttle issue" I don't mean to diagnose the problem. I just meant to describe the experience. It feels like the car is accelerating and decelerating slightly and rapidly - faster than any human could tap the either the throttle or brake pedal. I could believe that the SC belt is slipping though I don't know why it would only happen at these particular speeds and it appears to pass the half twist tightness inspection. I described the problems to Shad Huntley and he checked out the car so I'd imagine he'd look at those if they are likely causes, but I can double check myself. Need to look these up in the manual.

So far I've described this issue to Shad Huntley, Don at Hilltop and Jim Russell and none seemed to be able to figure it out. The only suggestion so far has been a standalone EMS.

RYU said:

Can you explain this more?
" sometimes throttle oscillates when moving from acceleration to constant throttle around 70-90mph"

Your car is a 92 which has cable/manual throttle. The ECU has no control over throttle the way it seems you're describing. The ECU can only add more fuel or adjust timing. It cannot add more air explicitly. The way air can enter the system is via a vacuum leak or possibly a faulty Idle Air Control Valve. You might want to clean that or check if it's faulty.

As Jason said, a cracked bypass hose would cause a vacuum leak.

Click to expand...

You live in SF, why not take the car to Shad? Don't get me wrong, there are some smart people here. But it just might save you the headache.

Hey Jinks,

Shad installed the SC and I did take it back to him to try to address it already. He was able to make the idle a bit better but it still has issues and the "throttle" issue wasn't fixed - he suggested a standalone EMS might fix it. I'd be happy to do so again if he had a solution and I could get in touch with him.

Jinks said:

You live in SF, why not take the car to Shad? Don't get me wrong, there are some smart people here. But it just might save you the headache.

Click to expand...

Can you log AFR while driving? That could go a long way to determining if the tune/management is an issue.

Do you happen to know if there's a way to do that with OSX? It looks line an emulator and Windows 10 will cost $200.

jwmelvin said:

Can you log AFR while driving? That could go a long way to determining if the tune/management is an issue.

Click to expand...

stevedekorte said:

Do you happen to know if there's a way to do that with OSX? It looks line an emulator and Windows 10 will cost $200.

Click to expand...

It depends on your AFR gauge I suppose. I use the Zeitronix setup, which can log live to a Windows program, but can also log to an SD card through a datalogger add-on.

A slipping belt has a subtle affect to acceleration. Definitely not abrupt like you're describing. I do not believe this has anything to do with a slipping belt IMO.

My "guesses" still stand. Hope you figure this out! Must be frustrating...

jwmelvin said:

It depends on your AFR gauge I suppose. I use the Zeitronix setup, which can log live to a Windows program, but can also log to an SD card through a datalogger add-on.

Click to expand...

I installed Parallels, Windows 10, and the AEM FIC 6 and 8 apps. I can't get the Setup menu in either to work (car is running and USB to AEM cable is connected to laptop) in order to start logging data. Anyone here that's done this before have any tips?

Are you connected to the FIC? The icon in the toolbar turns green if I remember correctly.

Do you have an AFR gauge providing a signal to your FIC?

RYU said:

A slipping belt has a subtle affect to acceleration. Definitely not abrupt like you're describing. I do not believe this has anything to do with a slipping belt IMO.

My "guesses" still stand. Hope you figure this out! Must be frustrating...

Click to expand...

Which of your guesses were for which issues? I don't have time to do serious car work. Do you think I should take the car back to Don at Hilltop or Jim Russell (both have had the car before for other work and I've described these issues to them but they had no suggestions) to ask them to specifically look at the bypass hose and Idle Air Control Valve?

Unfortunately, those experienced guys could probably care less about what us internet technicians think. FWIW, and from our limited ability to diagnose online I think it's either the IAC valve or a intermittent vacuum leak. Why not run these posibilities with your mechanic, who's actually seen and experienced the problem in person, for their opinion?

The IAC valve is sold by Autozone apparently. Though not sure why they show 2 different kinds. I'll take a photo of one by my car now...
http://www.autozone.com/engine-management/idle-air-control-valve/acura/nsx

Nevermind.. I can't fit my phone in there to take a photo. I might ask your mechanic(s) about the TPS sensor also.

Sorry we can't be more help. Playing Internet Doctor is not always easy.

RYU said:

Nevermind.. I can't fit my phone in there to take a photo. I might ask your mechanic(s) about the TPS sensor also.

Sorry we can't be more help. Playing Internet Doctor is not always easy.

Click to expand...

Thanks Ryu, I appreciate your help here. I think I'll take it to Don next week and have him look at those. Not sure he's very experienced with boosted NSXs but these sound like things he should be able to check/fix.

jwmelvin said:

Are you connected to the FIC? The icon in the toolbar turns green if I remember correctly.
Do you have an AFR gauge providing a signal to your FIC?

Click to expand...

I don't have any gauges (I didn't want any changes to the OEM interior). I connected my laptop (running the AEM FIC app on Windows 10 on Parellels on OSX, lol) to the USB cable Shad installed behind the passenger seat which is connected to the AEM FIC unit. I noticed that one of the AEM videos mentioned some switch on or near the FIC unit that needed to be turned on for logging but haven't had a chance to look into that.

The switch is only for triggering internal logging, not related to laptop logging. Sorry I can't help more with why your laptop isn't connecting.

You should also think about the vacuum line to the factory MAP sensor. In the original CTSC setup, that came off the bottom of the plenum and could get oil in it. Mine suffered from very strange problems for a while because of that. Blowing it out from the sensor end helped for a bit but I had to move the line to a tap in the side of the plenum for a fix.

I also had some issues with how the install before the FIC had tied into the MAP line. If you are not using a Boomslang (or equivalent) harness, or if you ever spliced into the OEM harness, I would double check any connections in the MAP wire. Redoing my connection if that wire got rid of some odd behavior not that different from what you report.

If you can fix your logging issue it may help because you would see any discrepancy between the OEM and FIC MAP signal, and would see any abnormal behavior in the TPS signal.