New owner, mechanical problems!

[simonasaur]

I’m the excited owner of my dream car. A 1997 black nsx with tan interior.

I bought the car on bring a trailer. I thought I was getting a pretty good deal. It needed a timing belt based on time since it had last been done, other than that. It had lower miles, 56k, nice exhaust, cam, and type r suspension.

When I got there the cars idle was bumpy at idle. Then the owner told me that was the cam. And then let it slip that it needs a $5000 computer to run correctly.

So so at this point I’m a little apprehensive about my purchase because that’s a big deal that wasn’t disclosed.
but I figure I’m already in, the car looks good. And I’m really excited.

So the car was advertised with full records from the owners 15years of ownership. When I came to collect the car the guy only had the title. I thought that was weird and told him so. So we called chris at science of speed, as that’s who’s always serviced the car. The owner said they were friends.

On on the phone Chris said that the records were too old for them to still have, and that the owner needed to find his complies and send them to me. I asked about the cams that were in the car, and chris said he couldn’t remember the specifics. I asked about the bumpy idle and he said that” I could add an additional amount of air into the intake tract. That may fix it. I don’t know. I’ve never done it before.”

so so now I have the car towed to a local shop and have the timing belt done. I get it back. Take it to a driving event. Have a great time.

A new new problem arisees.

when driving the the car about say 3000rpm. And realeasing the car out of gear. The idle hangs. It hangs at 2500 I think. And it will not drop down untill you roll to a full stop. So you can coast for any amount of time and the idle will be super high. Only after coming to a complete stop will it drop to 800 range.

In addition to this the car wont pass emissions testing here in Portland Oregon.

Has as anyone dealt with this problem? Can anyone offer any advise as to what to do next? The shop who’s currently working on the car has checked and rechecked so many things. They’re at a loss as to how to get the car to run correctly as well.

Any and all all help will be greatly appreciated!

Sam

 

[simonasaur]

Things that have been checked.
Vacume leaks
ecu for corrosion
all sensors
compression
timing

 

[natcc99]

Sorry to hear about the mechanical surprises. Hopefully with little effort, things will get squared away and you will enjoy your new car in its full potential. Don't feel bad...being the car is old, we all experience issues.

The following is just a wild guess, but take a look at the throttle cable. (There is another member here that had their snap a few times http://www.nsxprime.com/forum/showthread.php/209718-Bad-luck-or-what?highlight=bad+luck) I am not suggesting yours will snap, but instead a possibility that it's not moving freely.

I'm sure a few more suggestions will come from other members to give some ideas/input.

 

[Sulley]

We probably need some more detail about your location, so we can understand what smog issues you're dealing with.
I doubt you will be able to pass with any sort of cam. When I lived in CA, I could barely pass with just a set of headers
and many times it took several tries. Mine is an earlier model and yours is a later one with a better catalyst setup so maybe
it will work. Good luck.

 

[Sulley]

Sorry, just reread thread and saw Portland. I do seem to remember something about the high idle issue also.
I'll see if is comes back to me.

 

[SWFL_NSX]

Sorry to hear that you're having trouble. The hanging idle isn't overly common on the NSX, so you might not be able to get a lot of advice over the internet. I would contact my local NSXCA (NSX Club of America) contact and ask them for a mechanic in your area that knows these cars, and then have him troubleshoot the issue and do a healthcheck.

The cams are interesting-I don't think many aftermarket cams were produced for the NSX, so you may be able to figure out what you have with a little sleuthing. I'm not sold that they would cause a rough idle, but of course anything is possible.

NSXCA contact for the Northwest is Warren Woodcox-he's active on here as well.

https://nsxca.org/nsxca-regions/nsxca-regions-northwest/

 

[Lude_2_NSX]

Sam, welcome to NSX ownership!

This is my first concern:

When I got there the cars idle was bumpy at idle. Then the owner told me that was the cam. And then let it slip that it needs a $5000 computer to run correctly.

Is this an aftermarket ECU? Custom tune for the cam that was installed? Did the prior owner explain exactly why he knows that it needs a $5K computer to run correctly?

 

[simonasaur]

Thanks everyone for the responses!

So the car’s drive by wire.

The car still has the oem ecu, which I would need to preserve to pass the obd2 plug in test.

 

[mwagner10702]

The following is just a wild guess, but take a look at the throttle cable. .

Please do your homework. There is no throttle cable on a 1997. It is drive by wire (DBW) introduced in 1995. Only thing worse than a cranky car is people giving uneducated advise.

 

[docjohn]

Hmmm first off Chris is usually more precise about his work...people putting cams in na2 cars is rare....comptech and toda are most common...lumpy idle typical of big cams in american v8's ...not the mild cams made for nsx...I had cams on my 96 and idle like oem...you don't need a aftermarket "computer" for just cams, but you can use one with a tune but then you are getting into stuff a honest owner should disclose....sounds shady...most gunked up idle air passages/intake issues cause dropping idle near stall issues.

 

[mwagner10702]

From the service manual:





Was the following checked?
1) Throttle Position (TP) Sensor
2) Throttle Valve Control Motor
3) Accelerator Position Sensor

 

[natcc99]

Please do your homework. There is no throttle cable on a 1997. It is drive by wire (DBW) introduced in 1995. Only thing worse than a cranky car is people giving uneducated advise.

Pardon, I accidentally missed the detail that the car was a 97. Embarrassing, it was the first sentence. :redface:

 

[mwagner10702]

From the service manual (IAB and Troubleshooting)







I would run through the troubleshooting . . .

 

[mwagner10702]

In addition to this the car wont pass emissions testing here in Portland Oregon.

Scan and post the DEQ test report you received. I'd be curious to see where it is failing. Since you have an OBDII system I am assuming the DEQ tech plugged their test cable into the OBD port under the glovebox? Or did they just use the sniffer probe at the tailpipe?

 

[docjohn]

post vin

 

[mwagner10702]

. . . when driving the the car about say 3000rpm. And realeasing the car out of gear. The idle hangs. It hangs at 2500 I think. And it will not drop down untill you roll to a full stop. So you can coast for any amount of time and the idle will be super high. Only after coming to a complete stop will it drop to 800 range.

This almost sounds like a VSS (vehicle speed sensor) issue as you indicate the RPMs don't come down until the vehicle is stopped. What happens when you increase the engine speed to 3000 RPM (while stationary) then let off the throttle? Do the RPMs immediately return to normal?

What happens when you run up through the gears? Again, I am assuming you are shifting above 3000 RPM. Do the revs drop between shifts?

 

[simonasaur]

Thank you everyone for the response. I’m in California now and for 2 more days. When I return I will post the vin as well as the 2 failed tests. I will also forward the info and the guess to my shop in town that’s troubleshooting.

 

[simonasaur]

With the deq test they plugged it into the footwell. There were only 3 sending, and Oregon requires at least 4 to pass.

It doesnt “hang” when you rev it stationary. It’s only when it’s moving. And no the revs don’t drop. It makes it weird to shift because of the high idle.

 

[mwagner10702]

With the deq test they plugged it into the footwell. There were only 3 sending, and Oregon requires at least 4 to pass.

Most likely your O2 sensors. Sounds like one is bad. Unlikely this is causing your hanging idle issues though. The DEQ test result printout should have the specifics.

 

[mwagner10702]

It doesnt “hang” when you rev it stationary. It’s only when it’s moving. And no the revs don’t drop. It makes it weird to shift because of the high idle.

How about engine temps? When all this is happening is the engine at full operating temp? Does it also happen when it is cold? The reason I ask is that some of the the ECU functions are in open loop or closed loop depending upon engine (coolant) temp. This will make a difference when attempting to diagnose the issue.

What does the OBDII scanner indicate? Is the ECU throwing any codes when this happens? I'd have the scanner plugged in when driving to monitor the throttle plate position. Hopefully the scanner is a freeze frame type. This will help grab the code(s) when the issue actually happens.

 

[dirtbag]

Things that have been checked.
Vacume leaks
ecu for corrosion
all sensors
compression
timing

Recheck the TPS. Make sure the values are within tolerance especially when the throttle is closed; but also check throughout the entire sweep, and there are no dead or spiky spots. If the "computer" thinks the throttle isn't fully closed, it will do weird things like and idle hang, hunting, and so on.

 

[simonasaur]

https://bringatrailer.com/listing/1997-acura-nsx-7/
heres a description of the car. I’ll be home and back to a keyboard tmrw. Then I’ll be able to quote and respond to all the comments

 

[mwagner10702]

http://www.nsxprime.com/forum/showt...X-T-Black-Tan-6-Speed-62000-JH4na2168vt000169

Damn, this car has seen more hands than a prostitute's ass.

 

[Jinks]

320 BHP on a stock motor??? On oem ECU???

 

[Jinks]

Looks like SOS sold these camshafts in the past.52695-Revolution-Japan-Hi-Power-Camshafts