I have a 95 240sx that we just installed a turbo on. T3/T4. ECU is efispecialist set for tomei 555cc injectors, and Z32 mafs. Walbro fuel pump. Complete 3" exhaust. Timing set at 19 degrees. Altitude is 6700 above sea level. Car starts but runs very rich. a/f is around 10. tachs to about 5000 rpm then is so rich it won't tach more. Can't completely depress the throttle or it floods out. It helps to lower the fuel pressure to around 25 psi, but is still rich. Checked the maf and the voltage reads good. Intake air temperature sensor is not connected.

Question: I have read that there needs to be straight sections of pipe before and after the maf, but I notice a lot of pictures with the air filter connected directly to the maf. Sent email to efispecialist and they indicated that the air iats does not need to be connected. Any ideas are welcome.

uintasno wrote:I have a 95 240sx that we just installed a turbo on. T3/T4. ECU is efispecialist set for tomei 555cc injectors, and Z32 mafs. Walbro fuel pump. Complete 3" exhaust. Timing set at 19 degrees. Altitude is 6700 above sea level. Car starts but runs very rich. a/f is around 10. tachs to about 5000 rpm then is so rich it won't tach more. Can't completely depress the throttle or it floods out. It helps to lower the fuel pressure to around 25 psi, but is still rich. Checked the maf and the voltage reads good. Intake air temperature sensor is not connected.

Question: I have read that there needs to be straight sections of pipe before and after the maf, but I notice a lot of pictures with the air filter connected directly to the maf. Sent email to efispecialist and they indicated that the air iats does not need to be connected. Any ideas are welcome.

Hook up the IATS and see what happens. If it doesn't need to be connected then it won't make a difference.

Also, you need to get into the ECU and adjust the fuel delivery to the injectors. It's not an issue of pressure, it's an issue of volume.

Good luck!

Connected the iats and no difference. Don't know how to trim the fuel in the ecu. It is not programable. When I check the codes I get Iats and knock sensor. I think the knock sensor is going off because the motor pops and backfires when reved up. A/F is reading between around 12 then goes down to 10. It is a little better with the stock ecu and stock MAF, but still way rich.

Help. Update. Car is still running real rich. Here is what I have tried.
1. I checked the z32 maf with a volt meter. With key on the hot wire has 5 volts to the grounds. The grounds are tied together and connected to the wire harness ground. With the key on I get a low voltage, then when I blow across the sensor, the voltage goes up. I think the low voltage was around 0.7 volts and when I blow across the wire it goes up to around 1.5 volts. I get no code for Maf in the icu.
2. I checked the tps. I put volt meter across the output and ground and got around 0.1 volts with the throttle closed and 4.0 with the throttle wide open. It appears to be lineal between those two readings.
3. I have 2 ecu's for this car. The stock ecu and an older ecu that was burned by efispecialists.com. The second ecu has 2 sets of chips. It is set for z32 maf and 555 cc injectors. The previous owner had a second set of chips burned to try to clean up the bottom end, but he never installed them in the ecu. We just finished rebuilding the motor and initally placed the most current chips in the efispecilists ecu because we have the z32 maf and 555 injectors in the car. Runs very rich. Changed chips and still runs rich.
4. Was concerned about the waste gate setting, because the car had broken ring lands. Checked the presure required to open the waste gate with a compressor and pressure gage with the waste gate off the car. It was around 12 psi. Couldn't get another spring to lower it so I cut the spring off until I got it at around 8 psi the gate starts to open. I don't think this would cause a problem, but maybe?
5. Checked the blow off vavle to make sure it was staying closed during idle. It is.
6. Checked the 555 cc injectors with ohm meter and got 1.7 on all of them. Checked the stock injectors and got same reading.
7. I am getting no codes. If I disconnect the tps or iats. it does throw a code for those.
8. When we first started the car it was very rich. Finally changed to the stock maf and ecu and it runs better but very rich. Been checking every since. Yestercay I went back to the z32 maf and efi ecu and put the older chip in it and the car ran better but will not tach pas 2700 rpm. Just shuts down. Put the chip in thesame way the old one was, but became concerned about how the chip is supposed to be installed so set email to eifspecilasist and found our the chips are in backwards. May have ruined that ecu.
9. Decided to go back stock with ecu, injectors and maf. Will now tach past 2700 but still very rich and sporataic. Have checked the timing and have it set at 20 degrees. Have checked the timing chain and marks and they are correct.

I suspect the maf or tps, but have checked those and got no codes. I think they are good because of the no code. Any ideas what would make it run so rich with no codes. Exaust is black. Spark plugs are very black and sooted. I replaced the plugs with new ones. I do have a small exausst leak that started after i reinstaled the wastegate, but it is after the wastegate. Was not there prior so I think I have a messed up gasket after the gate. I doesnt seem to have changed anything, but I am fixing that this morning.

Any ideas would be appreciated. I am buying a vacuum gaugge this morning to see if I have a vac leak. I have sprayed starting fluid around the intake manifold to see if I could get any increase in rpm, but nothing. It is not just a little rich, but very rich.

pics of ur setup would help. U should locate ur maf 6 to 12 inches away from turbo if locating ur maf near the turbo. Some People also mount the maf close to the throttle body to avoid this problem and stalling issues. Also check ur maf wiring (type this in google search "jim wolf z32 maf" first one that comes up) Note the plug connector ridges (2 on top one 3 on bottom.) i know u dont have a code but please double check the wiring. a very large vac leak could cause this condition, comp seeing "extra" air,so its dumping fuel to compensate. try an get a hold of a smoke tester as they work wonders! hope this helps

Sorry about the poor quality, but it was dark. I think you can see the layout. The maf is below the elbow on the left side. I checked the wiring between the maf and ecu and the maf and tps and they are both good. The maf is wired correctly. It has the stock maf, injectors and ecu right now. Still has the same problem. Idles, but rich. If you step on the gas it stumbles and wants to die. I checked for vac leaks with propane and found nothing. Rechecked timing. Checked codes and the only codes I get are det sensor when I try to wrap it up and intake air temp. I have the intake air temp hooked up, but when I check for continuity through it it does not show cont. It may be bad. I also cannot get the wires to trace to the ecu. Don't know whats up there, but don't think it would make that much difference. efispecialists told me it shouldn't need to be connected.

Any ideas appreciated.

......honestly seems your testing testing testing too fast wasting time! THINK take it slow you done tested everything im starting to get scared here your running out of stuff j/k

Since you tried multiple ecus im gonna say NOT a problem dont look back.
You hit them up and they said not intake temp. ok so you DONT NEED it dont look back
Wiring good leave it

I would try a few things here. Disconnect sensors one at a time restting ecm each time(jump pos neg terminals to each other) and see if you catch a break there. Seems you never got the engine warm im guessing and same condition all time anyways ecm only uses a few inputs primary on cold start up ....

MAF/coolant temp/TPS thats normally bout it veryow minimal

No background on motor is saw in thread rebuilt? do a compression test real quick before you continue if any doubt

anyways good luck hate those situations

Thanks for the thought. I have never checked the coolant temp. I have trouble getting the engine to warm up, it is running so rich. Never thought about compression check because of rebuild, but I will check that tonight. I keep going back to the maf. I will try getting the engine warm then jumper the sensors. Good ideas. Thanks. I was going to take a video if you think it would do any good.

So are you saying you're running a blow through MAF setup?

No. I am not running a blow through maf. The maf is on the end of the 90 degree bend on the intake, and the air filter is connected to the end of the maf.

I cant see video helping ....ok ok... yep runs horrible .....


I hate to say it but you need to eliminate large areas or possible problems to narrow your testing.

Try bypassing complete turbo set up put maf off intake like oem and crank her up. When not in boost its essentially same thing. It will eliminate tons of posssible "intake leaks (bov/charge piping/intercooler/turbo itself seals *air not oil seals lol... )

Id set that up maybe get a idea on it!

That would eliminate alot of the Air circuit. AIR FUEL SPARK << being areas you need to narrow too

Spark being compression partly -- do the test

Fuel is going to suck here...hmmm........i dont have time to read back thru your set up but walbro 255 1 of them? Piggy back since your using 555 BIG like 2 pumps maybe problem there you did test pressure tho if i recall ehh......



-convert back stock fuel system stock ecu to eliminate wiring and sensor input for most part!!!!!<< this would suck but it would elminate almost all sensors and wiring problems leading to a big NARROW problems


again good luck hope you get it running sounds like you spent enough $

Ok, if you are running traditional MAF setup, try inducing a vacuum leak between the MAF and the turbo so it sucks in unmetered air. That should lean everything out for you. There are many ways you can do this (drill a hole in the pipe, get the couplers to fit loosely around their connections, bend the pipe in the coupler so that an exposed crack forms, etc).

At least at that point you can let it run (and even drive it) while you hunt for the root cause. Converting the intake system back to stock is a good idea too. That will quarantine the suspect area to something between your MAF and throttle body.

I am considering ordering an obd II scanner to see if I can verify all the senors are working. Is that worthwhile? I had not thought of the turbo loosing air. It would have to leak through the exhaust? Anyone seen that happen. Would have to be a major leak. How about plugging the filter end of the pipe and pressurizing the inlet from the maf to the throttlebody? I presently have the car back to stock except the turbo. I was going to disconnect the maf and place it directly ahead of the throttlebody, thus bypassing the turbo, inercooler, blowoff and all the intake piping. I will still be spinning the turbo, but will just let it vent to atmosphere. Good idea or bad?

By the way, I am looking at the scantool oblink sx with scan xl software. Anyone have experience with this unit?

I have a fuel regulator on the fuel line and can regulate the pressure. It is running at 30 psi, but I can turn it up to over 40 psi. Don't know what it will maintain when under load (damn thing won't run under load), but I am sure the pressure is adequate to make it idle and wrap up.

Id put fuel pressure to stock trim 42 roughly i think. < thats what your tune whould be set up for id assume


Yes you can run turbo just open not really a "good think but fine for short period. Obviously if its out of the loop and you put it under load with a beefy fuel system it will go super rich probly stall. More or less idea is to get it to idle smooth i wouldnt even leave the garage.

I picked up the Ultragauge while it was on sale. By far the best OBDII scanner I've ever seen.
http://www.ultra-gauge.com/ultragauge/index.htm

I checked the ohms of the coolant sensor and the voltage on the connection and both are good.
I bypassed the turbo, inercooler and all the plumbing and hooked the maf and air cleaner just ahead of the to the throttlebody. No difference. However we are now getting code 12 and 34. Knock sensor and maf. Am wondering if the maf in intermtant bad? Possibly both mafs are bad? Have a scanner comming so hope that will tell me something. I am going to try the z32 maf tomorrow. Don't think the knock sensor will make that much difference. It seems to run worse each night. Will only idle for about 15 seconds, then dies. If we give it gas, it dies. When I pull the maff off the intake, it doesn't seem to make much difference. Wish I knew someone local I could borrow a maf off (that I knew was good). I am going to check both mafs tomorrow again. Thanks for the suggestions.

PapaSmurf2k3, thanks for the suggestion on the scanner. Already ordered one earlier today. Should have it by Friday. It connects to a laptop and looks like it will at least give me information while the car is running. Its called scantool.net.

Cool. Where do you live?
You never know who is local. I have a spare S13 MAF.
You could try putting the Z32 MAF on with the stock injectors. That should lean everything out too.

I would def. look into the knock sensor code !!! I've had 1 go bad myself and heard many times of them going bad including harness problems!

I also hear all the time my maf is bad and then they try 3 different ones.....never to fix the problem. No saying its not bad just hear that ALL the time.


Is your mechanical timing right???? Its pretty easy to get it off when you jam the thing in there. Took me like 4 tries because you would assume it point to #1 but it actually ends up pointing at #2--> before it. Then again mine wouldnt even run till i got it right.



How about finding the resistance the ecm looks for at idle from the maf and giving it that resistance. <<you could use a fuel lvl. sending unit possibly to change the "signal".

^def. a simplified example theres 6?5? wires going to it incorporating intake temp. ??? eh anyways good luck again


You can also back prob the maf and watch voltage instead of looking a stream from obd2 or use it to reference/compare.

^then if its off mess with the sigal with say a safc NOT A FIX just trying to get ya running here

Just forgot about something!!!!!!!!!!!!! i bet i know what it is!!!!!!

had same thing kinda happen to me now that i think about it





Idle thermo valve<<<

It comes out fight next to throttle body coming from under the plenum. You route this pre maf. It ends up being essentially a intake leak being "unmetered air entering the system. I left it just chilling not hooked to anything and it ran BADBAD barley idle. RICH!!!

When you are saying the idle thermo valve, that is the large line that is next to the throttle valve? If so, I tried plugging it and it instantly dies. It is after the maf right now. It has a vacuum on it when running, so I disconnect it and it from the intake and leave it open and it doesn't seem to make any differenct. I would think that if it is supposed to be metered air, it would lean the engine out when disconnected, but it does nothing. Makes me think it is the maf.

I have checked my timing. Had it off one tooth originally, but redid it. Have it set at 20 degrees now and it seems stable idling.

I thought that the det sensor only retards the timing 5 degrees during detination? Its a real pain to get at, but maybe I can disconnect it and see if that does anything.

I have checked the maf for resistance and also for voltage output and both mafs were ok. I am going to recheck them tonight.

I am located in rural Wyoming so I don't have access to a lot of parts. I called a wrecking yard in Salt Lake City and found a j30 maf for $30.00, so I am picking that up when I have to go down there on Thursday.

I am hoping to get my scanner by friday, and hopefully that will help me.

It doesn't sound like the MAF to me. Hell, you can disconnect the MAF all together, and the car will still run and rev, just not passed ~3000 RPM or so.
You are right, disconnecting the idle intake hose from the system should make the vehicle run leaner, so long as it is disconnected from the negative pressure side of the turbo. From the positive side, you could be blowing off metered air. You are better off just leaving it hooked up.

Have you tried inducing the vacuum leaks on the negative side of the turbo (between the turbo and the MAF) like I said?

I checked the voltage on the maf again and it is reading within spec. I am presently bypassing the turbo. I have the maf attached to a an elbow and pipe just off the throttlebody. If I start the motor at idle with everything hooked up, it idles. If I step on the gas it pops and dies. If I open a hole between the maf and throttlebody, and start the car, it wraps up a little. Not to high, but it does at least wrap up a little. That is with a small 2mm hole. I am now thinking the maf must be good. Since I don't have the turbo connected I tried disconnecting the idle intake hose, but the car will not start. If I disconnect it when running and wrapped up, it sees to help, but it pops and dies if it drops below around 1500 rpm. It will wrap up to around 3500-4000 rpm with the induce leak.

Is there anything that makes major adjustments to the fuel other than the throttle position sensor. I have checked the coolant temperature sensor and it reads good. I checked the intake air temperature sensor and it reads good. The only code we get when starting and running the car is the knock sensor.

Almost sounds like your valve timing is off....

The timing was off by one tooth, between the cams. Fixed that and the car actually started and ran decent on the bottom. It has progrssively gotten worse. I changed the plugs to see if they were fouled, but that did nothing. May have to pull the timing and check again. Before I fixed the timing, I had to advance the timing to around 30 to get it to run at all. After adjusting it, it starts and is stable at 20 degrees. It idles good, just rich. If you gas it, then it stumbles like timing. I am wondering if there could be something in the distributer. I keep thinking that maybe its a combination of things and that the rich is unrelated to the bad running. All the emissions is removed and I bought the car that way. Don't know if something there could be causing the problem, but I haven't found anything yet. Odd thing is that I am getting no codes. I would think that if there was something serious with sensors that I would get a code. I am hoping to get my scanner by Friday and it may tell me something. At least I can have a second check on the individual components.
Could the O2 sensor make this much difference? I haven't disconnected it and checked it, but I also get no codes for it. I keep thinking that for something to make it run this bad, it must be the maf or tps. They both check out.
Any other ideas are welcome.

The TPS doesn't make that much of a difference, especially at idle. Neither does the O2 sensor, especially during open loop operation (which it sounds like you're in seeing as how it never really runs long enough to go to closed loop). Exactly HOW rich are you running? Do you have a wideband on the car?
You really have to be below 11:1 AFR before you really start running bad. Below 10 is where things start to get dicey.

Can you put your engine at TDC and take a pic of your cams?

If your disconnecting sensors and not getting codes you have a problem i would imagine. Especially something like the oxygen sensor which should throw a heater circuit code pretty quick...... Just go stand alone hehehe

The car has an a/f reader on it. Don't think it is wideband. It appears to only read down to 10:1 and that is where it is . If I get the car to wrap up a little, it will go to around 11:1, but thats it.

The car does throw codes if I unhook the sensor. Haven't tried the O2, but it does for the maf, the throttle position, the intake air temp, and the coolant temp. Whenever I unhook them it throws a code. When I reset and reconnect the codes go away and the only one I get is knock sensor.

I am going to check the cam position sensor tomorrow. It is too cold after work right now. It is supposed to warm up this weekend and I am going to pull the timing cover and recheck the timing.

You should really be able to induce vacuum leaks to get the A/F ratio to lean out... unless your gauge is reading incorrectly. Is black smoke coming out of your exhaust?