Hey! I recently purchased a S2000 2003 with a Comptech supercharged installed and it only has got 12,000 miles when i first got it. Now comes the problem when
the check engine light will come on and the car will get to the point where it will not boost at all. At this point, if you take it above 3000 rpms, it drops way down and then bucks violently until you shift and take the rpms back below 3000. Once I reset the ECU, it drives fine for another month, but then the problem reoccurs.
This is because its still running on the standard ECU? do i need to install a new ECU? Could it be its running to rich in fuel? Please help determine this problem.
thanks

 

Check the FMU, it allows you to run boost on a stock ECU.

I would look into getting a Greddy Ultimate ECU and a tuner in the future

 

Thanks for your help iDomN8U,
So that mean i have to replace the FMU? or just check to see if something is not right? I want to buy the a Greddy Ultimate ECU, but a tuner in my country (LAO P D R) is very hard to find. I import my car from USA with a comptech supercharged installed. Is it hard to tune it yourself with the Greddy Ultimate ECU? How about the VAFC? is that important to help the car or jus the a Greddy Ultimate ECU is enought? Please help?

 

Post in the Forced Induction Section, you will recieve much more help there

 

Totally need to get to this to the FI forum for better exposure.

Whats the history behind the car and the setup? Stock boost, are you running the kit with aftercooler? Have you been to the dyno to check AFR? What type plugs, what gap, and what do they look like? Has the car run fine before? Have you done anything different since this started happening, i.e. made any changes to the car?

Personally I wouldnt even drive the car until you got it figured out and I certainly wouldnt be trying to force it while its throwing a CEL and bucking when you're driving it.

I'm FAR from an expert but I can give you some common sense pointers with this.

First I'd pull the plugs and take a look at them, make sure they're fine and gapped correctly. Somewhere in the range of .030 - .036 seems to be the commonly accepted gap.

If that checks out I'd check the wiring on the Comptech ESM. It's only four wires so it should be easy to trace, there's one power, one ground and then the two wires that help to "clamp" the MAP voltage. If you search in the FI forum for Comptech EMS there's a few threads with diagrams. If the wires are crimped I'd suggest soldering the connections to make sure they're right.

After that I'd suggest investing into a fuel pressure gauge, there's a nice kit that summit sells that has the adapter to use on the fuel rail and a small under the hood gauge. You need to pull the vacuum line off to see what the static fuel pressure is at idle. I believe Comptech ships the kit with the RRAFPR around 47-54lbs (I'm running 65 lbs on the stock kit and its where it needs to be).

If ALL of that checkes out fine and you're still having issue time to get that car to a tuner before you do anything else, that would be when I would be inclined to have a leak down and compression check done to make sure the motor is healthy.

 

Thank you ThatPreludeGuy!
The S2000 comes with Comptech Supercharge kit with no aftercooler, all i did to the car was replace the stock exhaust to HKS dual exhaust thats all modification to engine other than that (hardtop, advan rims 17", and Carbon hood & lips). Panda looking! The was never Dyno before.
Today i took my car to check for plugs, MAP Voltage and compression, everything was find the compression normal 140psi for all 4 plugs. However the Fuel pressure guauge was at idle on 35lbs so the machanic adjust it to 50lbs as you suggested (47-54lbs).
So by adjusting this fuel pressure will this solved my problem with the Check engine light on? or still have to look into a new ECU?
If so which is better AEM 1012 or Greddy Ultimate? So i can install and tune and Dyno it to see the new result.

 

i thought the S2k motors should be closer to 200 psi across the board? Also was the fuel pressure adjusted as static (i.e. vacuum line disconnected) and was it done while checking the A/F ratio? I wouldn't go making adjustments without knowing what you're doing. Also you said you checked the plugs, what type of plugs where they and what where they gapped at. I think you need to provide all the information in order to get a fair assessment of whats going on with the car.

 

Sounds like your FMU. I'd get it replaced or junk it and get a Synapse Missing Link. They both do the same thing. It could also be the wiring on your FMU. Check for solid connections.

 

Sorry my mistake it was 195 psi across the motor board, yes the vacuum line disconnected during fuel pressure adjusted same with A/F ratio. Plugs i didn't note down what type and also the gapped didnt check. just check if its still good, and it is. I got to get back on the type of Plugs and the gapped later on. But after adjust the fuel pressure (by tightening the screw on the fuel pressure increase from 35lbs to 50lbs) it feels alot better when driving, Check engine light hasn't come on yet so thats a good thing. But If it did and i have to reset the ECU again do i have to adjust the fuel pressure again everytime i reset the ECU by disconnecting the battery?
Thanks for following up ... (i love to drive but poor in machanic) HELP!

 

Well I'd still pull the plugs, note the brand and type and check the gap. Do you have a printout you can scan and post of your AFR? Checking the ESM wiring is a good idea as well, I've never had an issue with it but there have been a good number of people that have due to faulty connections (wire splices instead of soldering etc...).

Reseting the ECU will not affect the fuel pressure as that's being set mechanically by the RRFPR. What's the condition of the vacuum line attached to it, if its cracked or crimped it could give some problems if it is.

Two other things to check for good measure would be the tightness of the belt as well as making sure all the connections are tight and sealed on the kit, the elbows etc...