Ghost problem with my sr20det. Need anyone who is an expert on these motors.

[newdude1]

Well I have been having this problem with my car running crappy below 3k rpm's. I would drive it and it would be fine for a bit then the vac will drop down to 10 and the car will start bucking then it would correct its self.

So after trying to check for leaks, voltages, etc I ended up taking the car to a local shop. They did a boost leak test. No leaks anywhere. Check the maf and tps voltage. All good. Checked the fuel pressure and all good there too.

So they said maybe if they threw it on the dyno that they could check the afr. So I agreed and they found out I am running extremely lean below 3k. Here is what the afr did1500- 17.72000- 16.5 2500- 163000- 14.53500- 13.84000- 13.64500- 13.55000- 135500- 12.86000- 12.5

So after seeing that I thought it was deffinatly in the tune. I have a JWT. My set up includes front mount, bov, 740cc injectors, z32 maf, gt28r. I called JWT and they basically said its not in the tune. So now Im stuck and need some ideas on what would cause this?

JWT wanted me to run all these test with a consult but my wiring harness doesnt have a port for one. So I need some ideas on how I can fix this or what would cause this?

[rc1honda]

Sounds like a MAF problem. Im not sure but do you have to run a Cobra MAF with JWT. Maybe your MAF is dirty, faulty, or not wired right.

Also for JWT to say it's not the tune is horrendous. How the F do they know it's not the tune? I would of asked for someone else. "Not the tune" is a unacceptable answer. The A/F ratio is way and the ECU controls A/F ratio. At least give a option to send it back for diagnostics. Call back and tell them want your money back and i bet they will change thier attitude.

Also a good idea is to open the ECU and make sure the sip on the inside is firmly in place. After shipping the rom chips can get shaken loose or make a bad connection.

Also you can check your injectors, Any and all sensors. Pull codes for the ECU. Time to bust out the multi-meter. You said a shop went throught the car and can;t find anything? There has to be something, and if not then it's the ECU.

Also it helps to have a friend with a EMS. They can put thier EMS in your harness and check the sensor and voltages. It also kinds sounds like a fuel pressure, fuel pump problem. On the dyno did the moniter fuel presssure along with with the A/F? Also your running lean throughout the power band not just under 3K which also makes it look like the tune. Was it WOT testing or just a nice roll of throttle to 6,500 rpm. If it was WOT testing then it definitly is the tune. 12.5 AFR at WOT under load is to lean. Should be 11.4-11.7 ideally but at least 12.0 just to be safe.

Modified by rc1honda at 3:33 PM 1/11/2010
Modified by rc1honda at 3:36 PM 1/11/2010

[newdude1]

Well when I ordered my ecu I told them I was using a z32 maf. And the voltage has been checked by me and the shop.

Tps is inspect for voltage.

They shop checked the fuel pump and injectors. Everything is inspect there too.

And the dyno was done at wot...

So I think Im going to be calling back tomorrow and hopefully get ahold of them this time. Because I am out of ideas.

Any one else have any ideas what could cause this?

[LayNLow240]

Check your fuel pressure, and find out what JWT was tuned for as far as fuel pressure goes.

[rc1honda]

Check your fuel pressure, and find out what JWT was tuned for as far as fuel pressure goes.

Thats a good idea too. Base fuel pressure is needed. Also at WOT 12.5 is way to lean. Sounds like a bad tune. Could be a O2 senor or the CTS sensor though. i would check these 2 sensors too.

[Madriftshocker]

I'm don't think that the 02 is used by the ECU at WOT, can't hurt to look though. I'd check the boots on the COP!! I know that my car did many screwy things and I had one with a crack in it. Looked like dry-rot cracks at first. Hope this helps if not good luck.

[newdude1]

whats the COP?

And Ill find out what fuel pressure they normal use but I was under the impression its stock.

And Ill also check the CTS sensor.

But the weird thing is, is that the car ran perfect before the tune, injectors, maf, and turbo. And the maf checked out fine and the injectors did too. This is the reason I think its in the ecu. I called JWT and they said it cost 25 bucks for them to check it so Im going to do that and see what happens.

[LayNLow240]

whats the COP?

And Ill find out what fuel pressure they normal use but I was under the impression its stock.

And Ill also check the CTS sensor.

But the weird thing is, is that the car ran perfect before the tune, injectors, maf, and turbo. And the maf checked out fine and the injectors did too. This is the reason I think its in the ecu. I called JWT and they said it cost 25 bucks for them to check it so Im going to do that and see what happens.

It will be cheaper and quicker to find out what they have fuel pressure set at for their tunes, and to check yours than to send your ecu off. If you find low pressure then there will be no need to send your ecu off just yet. You could have leaky lines, dieing pump, or the pump might not be getting a full 12.5V throughout the rpm range, vac leak at the fpr, dead fpr. You will narrow down a lot of things by checking it. And just because the shop "said" the fuel pump was good doesnt mean they are right, or if they even checked it.

[newdude1]

I understand about the shop saying they did something and actually didnt, but the place I went is a legit shop. And Ill look into what the fuel pressure should be at.

[Madriftshocker]

The boots on the COP (Coil On Plug) is what i was referring to. Didn't mean to throw you off. If you know anyone that has another working maf that you could try, it might not be a bad idea. MAFs sometimes act differently on a tester than they do on a car.

[newdude1]

Ok will. Do but I think I figured it out. My timing was way advance. But my car still wont run right until it warms up completely. Like my vacuum is at 10 and car just bucks when I try giving it gas. But once its warm it drives fine. What would cause that?

[Madriftshocker]

sounds like a possible CTS issue but i think that you had already checked that.............if not that then P.o.E.

[newdude1]

So I just installed a new fuel pressure regulated and its still doing the same thing. Im about to install my wideband and see what that says.

But what would cause the vacuum to drop randomly by its self? Any ideas?

[newdude1]

And I already replaced the CTS.