Going MAD here. Need Help

[The Mid]

Bought my first 91 s13 coupe about a year and a half ago and it was running like crap. Guy I bought it off of seemed like he threw in the towel and sold it. Keep in mind it was a completely stock CA at the time.

When I went to go check it out it ran fine passed idle. He slid it to show me that it ran fine but idled like crap. He had to stay on the pedal to keep it alive. Told me it was vac or boost leak. The day after I bought it I went hunting for this "leak" but didn't find a thing. Motor was all rusted and beat blowing black smoke like crazy. Pulled the plugs and they were fouled to hell so I thought it nedded a new head gasket. Since I was there I figured might as well just rebuld the entire motor.

I pulled the motor out and it took me about a year to finish since I machined it at school and assembled it in my garage.
By the time I was done with the motor this is what it had;

- Butterfly delete (Made sure everything was plugged up nice.)
- Surfaced head
- Decked Block
- Honed .020 over
- CP Pistons
- K1 rods
- Tomei 256 Poncams
- T25/T28 Isis turbo
- Trust timing belt
- Clevite main Bearings
- ACL Rod Bearings
- OBX manifold
- New OEM Oil Pump
- New OEM water pump
- New PCV valve
- Oil Catch Can Between cover and intake

Dropped the motor back in and it still ran the same. Had to stay on the pedal to keep it alive and smelled rich as F***. Automatically I figured it was going to be a sensor or a couple sensors that were causing this. Again I went hunting to no avail. Replaced coolant temp sensor, TPS, 1m ohm Knock Sensor bypass (conector was gone), ignitor, and drop resistor. Cleaned out the Idle valve set up and used all new OEM gaskets...no leaks and no change.

After that I had saved up to get myself a Nistune board. I looked for the serial number on the ecu cover that nistune needs but it was faded as hell and I couldnt see it. So I thought I'd open up the cover to mabe see if there was a number inside I could use. What I found was a Socket with a ROM chip as well as "550cc and Z32" written on the inside cover.

Frustrated at this find instead of getting a new ecu and nistune, I bought the following.

- DW 550cc injectors
- Nismo FPR set to 40psi
- Walbro 255 pump
- z32 MAF
- Innovate LC-2 Wideband

Changed everything out still ran like @ss. I've gotten it to idle with no load. I took it out for a spin a couple weeks ago around the block and there was no throttle response under load. Had to clutch kick to get it up to speed (Guessing limp mode here?).

A Couple days ago I go to start it up and now it won't even idle. I've had to feather the throttle to keep it alive. If I open it too much it backfires through the intake (very bad). Pulled off the MAF connector and it idles perfect at around 2000-2500 rpm with a stoic a/f ratio but dies when the throttle is messed with or the maf is plugged back in. It's a brand new Isis z32 MAF too and I've tripple checked that the wiring is done right. I've changed out my plugs numerous times and ckecked all of my sensors too many times. ECU shows code 55 also. I still don't know what it could be and I don't want to give up on it. This is my first post on here but I've been on this forum a lot searching for possible answers.

I'm guessing it's a Sh*t ROM chip, a bad harness, or a bad MAF. It's been almost 2 years since I've bought it and I want to drive it already.

Any help would be greatly apreaciated

[float_6969]

It should flood out and die if you put 550's in there and then unplug the MAFS. When you unplug the MAFS, the ECU no longer gets it's info from the ROM, but from another part of the ECU. If the engine doesn't have stock injectors, it should flood out in limp mode.

This sounds like a wiring issue to me. Can you swing a new wiring specialties harness? That would eliminate any chance of wiring issues. I would also source a known, good, STOCK ECU. Put those in, switch back to stock injectors and MAFS, set the fuel pressure to 35psi, and see where you are.

If that doesn't work for you, the next step would be to start tracing wires. My guess is it wasn't wired up correctly and there is something wrong. It's also possible. that the ECU was damaged in the past from a bad ROM, or improper wiring. It's ESSENTIAL that you KNOW the harness is COMPLETELY right before you try another ECU. If you have a bad harness, you could fry the new ECU and not even know it.

To trace wires, you'll need a continuity tester, a long piece of wire, the big wiring diagram from the FSM and A LOT of time and patience. Go through each wire, make sure it's on the right pin on the ECU and that it ends up where it's supposed to end up as per the FSM.

[The Mid]

It should flood out and die if you put 550's in there and then unplug the MAFS. When you unplug the MAFS, the ECU no longer gets it's info from the ROM, but from another part of the ECU. If the engine doesn't have stock injectors, it should flood out in limp mode.

This sounds like a wiring issue to me. Can you swing a new wiring specialties harness? That would eliminate any chance of wiring issues. I would also source a known, good, STOCK ECU. Put those in, switch back to stock injectors and MAFS, set the fuel pressure to 35psi, and see where you are.

If that doesn't work for you, the next step would be to start tracing wires. My guess is it wasn't wired up correctly and there is something wrong. It's also possible. that the ECU was damaged in the past from a bad ROM, or improper wiring. It's ESSENTIAL that you KNOW the harness is COMPLETELY right before you try another ECU. If you have a bad harness, you could fry the new ECU and not even know it.

To trace wires, you'll need a continuity tester, a long piece of wire, the big wiring diagram from the FSM and A LOT of time and patience. Go through each wire, make sure it's on the right pin on the ECU and that it ends up where it's supposed to end up as per the FSM.

Thanks for the reply float. I appreciate it.

But yea I was planning on pulling the harness and tracing wires these next few days but yea I think I'm just going to pick up a wiring specialties harness as soon as pay day comes around to be 100% on wiring. Whoever did the swap did a very bad wiring job and I've straightened out a couple little issues here and there in the harness but it's still sketchy. I was looking to wire in the Wideband signal to the ECU and the signal pin on the ECU was wrong. When I wired up the power and ground wires on the wideband from the stock location on the harness it shorted out my lamda sensor

As for the ECU I'm pretty sure there's something up with that also. I've unplugged sensors and no trouble codes show up when in mode 3. My stock injectors were done with so I threw those out. The stock MAFS looks new so I'll see what I can scrape together since I'm a bit low on fund$ at the moment.

For sure though I'm going to try putting eveything I can back to stock with exception of the Cams and the Turbo. Not just a pain in the rear but the turbo the motor came with was blown and whining with bent compressor fins. It was an ebay turbo and a lot smaller than t25.

As soon as I get that $$$ in my acount this friday I'm ordering the harness. If it sorts out the issue then I'm ditching the chip and going Nistune. If it doesnt then I'll save up again and source a set of stock injectors as well as an ECU.

I'll still pull the harness out tomorrow and see whats up with it.

Thanks again man really appreciate the input

[float_6969]

Yea, don't worry about the cams and turbo going back to stock. You're going to be SO happy with that wiring specialties harness. Honestly, if that harness, and Nistune had been around back when I bought my standalone, I'm not sure I would have even bothered with going standalone.

You should be able to pick up some stock injectors for next to nothing. boostboy might be able to hook you up if he ever pops in here, I haven't seen him on here in a while. Same goes for a stock ECU.

Well regardless, keep this thread updated, regardless of the outcome.

[The Mid]

Yea, don't worry about the cams and turbo going back to stock. You're going to be SO happy with that wiring specialties harness. Honestly, if that harness, and Nistune had been around back when I bought my standalone, I'm not sure I would have even bothered with going standalone.

You should be able to pick up some stock injectors for next to nothing. boostboy might be able to hook you up if he ever pops in here, I haven't seen him on here in a while. Same goes for a stock ECU.

Well regardless, keep this thread updated, regardless of the outcome.

Haha yea I've been wanting Nistune since I first knew about it especially for my power goals. For now though I'm hoping that it's only the harness that's causing all this ruckus. I'll keep looking for stock injectors and ecu. But Definetly I'll keep this tread updated.

[float_6969]

Good luck!

[The Mid]

Good luck!

UPDATE!!!

Got My Wiring Specialties Harness in yesterday. UPS blows so it took a while.

Anyways I just got done putting it in and it runs a TON better than it did before. Took a couple cranks to get it started only because it's been sitting for a couple weeks. Idles perfectly and doesn't die at idle like it would before after giving it throttle. I don't have a stock o2 sensor so I ran it with no o2 sensor and it ran rich of course but it wasn't backfiring like crazy. At idle it rarely misses. Under no load the throttle reposnce is still laggy but it doesn't backfire through the intake anymore when I randomly turn it to WOT. Two things I did notice was that the fpr was losing pressure slowly (vac leak somewhere) and more importantly...timing was WAAAAAAAAAAAYYY off. It was at least 25 to 30 btdc. It ran ok at 20 btdc but wasnt as good as where it was. When I placed timing at 10 or 15 btdc the throttle respomce would go to crap and it would backfire through the intake if I went WOT too fast. Bad so I left the timing where it ran the best. I'm going to wait until I have that o2 sensor to mess with timing so that I know the ECU sees the af ratio and I'm not in open loop all the time. Not ready to hardwire the wideband into the harness yet either only because at idle the ratio is still at 23.3 or so. I'm gonna have to go in and change the voltage values in the wideband before anyting happens. I checked the teeth on the timing belt and it is set perfectly so I'm not sure what's going on timingwise

So I took the car out to the street and it does run better than it did before. Builds speed better unlike before only reallllllly laggy. Laggy but doesn't feel like limp mode anymore. I'd say i was only going 15 to 25 mph flooring it in first gear. second would pickup up a bit but even slower responce. I needed to slip the clutch a bit to let it build speed. Clutch adjustment, maybe new or remachine my flywheel?

I'm guessing I'm just going to have to ditch the ROM and get myself a nistune board. We'll see what happens when I get the o2 sensor. But still any other ideas would help. Might see something that I'm not. Thanks again

[float_6969]

That REALLY sounds like the cam timing is off. I know you said you checked it, but I've seen A LOT of people SWEAR the cam timing wasn't the problem and it turned out that it was. It's not hard to do right, it's just really easy to do wrong.

[The Mid]

That REALLY sounds like the cam timing is off. I know you said you checked it, but I've seen A LOT of people SWEAR the cam timing wasn't the problem and it turned out that it was. It's not hard to do right, it's just really easy to do wrong.

What's fuuny though is that before I changed the harness the timing was set at 15 degrees but ofcourse it wasn't even idling right and dying a lot. The cam gear marks are right on the two marks on the plate behind the gears and at TDC on the crank but then now with the new harness in the timing is way off. I'll check it again and I'll post pic tures of it. or you can just look me up on instagram "tomorrowsmidnight" and I have pictures and vids of what's going on so far. If anything though it'll have to wait till friday since I work all day these next two days. Another thing...could it be the CAS that's going bad? Just thought about it right now.

When it came to putting the timing belt on, the tensioner spring was the sketchiest part of that whole deal. I felt as if there was not enough tension coming from the spring so I used the allen key and gave it a bit more tension to take away the play in the belt then tightened the bolt down with red loctite. The bolt probably gave and now the tensioner could just be floating around messing with the timing? For sure though I'll take a look at it and see what's going on. I'll keep you posted though.

[float_6969]

It could be a bad CAS I guess, but they're not usually off like that. If the tensioner is potentially sketchy, you need to inspect it ASAP. If you break/slip a timing belt, you'll bend valves instantly.

As for putting extra tension on the belt, it can make the belt ride off center of the gears and wear the tensioner out pre-maturely.

[boost_boy]

I would really re-inspect the physical cam timing as float suggested. From what you are saying, your engine sounds way too lazy and probably running ridiculous egts. My biggest concern is that your engine is not fully broken in yet and your are having ECCS issues (Not good for the physical motor). You should really focus on getting that engine to run correctly by putting it back to stock, so that you can properly break-in that motor. If not, you're going to rinse-down those cylinder walls with fuel and ruin the rings and the engine's break-in period.

[The Mid]

I would really re-inspect the physical cam timing as float suggested. From what you are saying, your engine sounds way too lazy and probably running ridiculous egts. My biggest concern is that your engine is not fully broken in yet and your are having ECCS issues (Not good for the physical motor). You should really focus on getting that engine to run correctly by putting it back to stock, so that you can properly break-in that motor. If not, you're going to rinse-down those cylinder walls with fuel and ruin the rings and the engine's break-in period.

UPDATE!!!

Thanks for the input Dee. That's why I'm getting more and more frustrated with this motor since I haven't been able to break it in properly because it's running like crap.

Anyways today I rechecked my timing and all of the marks lined up perfectly no matter how many times I turned the motor over. The only thing I wasn't happy with was the timing belt tension. It was too tight so I loosened it by just a smidge.

So after putting the belt cover and the CAS and wiring back on I fired it up. Took a couple cranks and a bit of throttle to get it started and idling. Ran just as it has been now that the new harness is in. Set the timing to 15 degrees btdc and it idled perfectly. After shutting the motor off for a bit I got curious as to if the ECU would throw codes now that the wiring is straight. Put to mode 3 and it threw code 21 for the ignition. I called since it's been idling fine just not much power under load.

Now that I knew that code 21 was being thrown I thought it would have been the CAS that was bad since the last time the motor ran the timing was waaaaayyy off. Curiosity carried me to start unplugging coils. So I fired it up again and started unplugging coils. Turns out my #1 and #3 coils are DEAD all I could say was F*CK and felt dumb since I should have checked those from the very beginning. There was no change in the idle with both those coils unplugged. Exhaust runners weren't hot at all so it comfirmed the lack of spark.

I know there is signal to those since I set the timing with the induction pickup on the #1 cylinder. But yea it looks like my problem has been bad coils this whole time F*CK.

So I'm going to take care of those and then come back with another update hopefully within a week or so depending when I get those coils in. Thanks again for the input guys I really apreciate it. Hopefully new coils solve the problem.

[float_6969]

Be aware that the test that you performed only narrowed the issue down to those cylinders, not necessarily the coils. You could have bad injectors on those cylinders as well.

[The Mid]

Be aware that the test that you performed only narrowed the issue down to those cylinders, not necessarily the coils. You could have bad injectors on those cylinders as well.

That is very true but the only reason I said coils was because I have brand spaking new Deatschwerks in there. They don't even have a mile on them yet haha Also it smells a lot like gas and the motor tends to backfire every now and then when idling on just the two cylinders. I just got home from ordering the coils. They shoud be here by tuesday. I'll update on wednesday for sure though. While I'm in there I'll double check the injectors just to be safe

[boost_boy]

I'm glad you are narrowing down your issues, but I hope all those issues haven't screwed-up your break-in period. I wish I can fix all you guys' issues, so that you guys can enjoy your investments instead of this set back or that issue. That is why video of all idling or driving issues are paramount in helping the forum help you guys solve your dilemmas. Be sure and re-check your ignition timing once you get replacements coils for the two bad ones.

[Izento]

Nice, hope you have solved all the gremlins.

[biosehnsucht]

Oh man, I was driving on 2 cyls for a couple weeks once... before I had it tuned just right, it was hard to tell the difference between 4 cyl and 3cyl, so when the 2nd coil pack ate it, I was like "damn, lost a coilpack! Running on 3 cyls!". If I hadn't checked them ALL out of OCD I'd never had realized I was 2-banging it for awhile ... and been back to 3 cylinders instead of 4!

It was a bit sluggish but it got me to and from work just fine and boosted "fine"

[The Mid]

Oh man, I was driving on 2 cyls for a couple weeks once... before I had it tuned just right, it was hard to tell the difference between 4 cyl and 3cyl, so when the 2nd coil pack ate it, I was like "damn, lost a coilpack! Running on 3 cyls!". If I hadn't checked them ALL out of OCD I'd never had realized I was 2-banging it for awhile ... and been back to 3 cylinders instead of 4!

It was a bit sluggish but it got me to and from work just fine and boosted "fine"

UPDATE!!!

So I changed my coils and no change. Got frustrated and realized only two things could be messing up with the ignition system. Checked igniter it was good then I looked over to my drop resistor and the wires for my #1 and #3 injector were frayed and not making contact with the actual resistor. So I took it off and soldered them back on as a temp fix, plugged it back in..........PERFECT running on all 4's with instant throttle response and pulled hard when I took it out for a roll around the neighborhood. Still a very feint and random backfire but I still don't have an o2 sensor. So I'm getting a new resistor and problem has been solved.

Thanks again guys I really appreciate all the input you guys have given me and I should have seem those wires in the back. I knew it was going to be something dumb and overlooked.

[float_6969]

Glad to hear you got it sorted out!

[boost_boy]

Well done