jjschafe

The car is a 99 Civic LX with D15 bottom end, D16y7 head, D16y8 intake mani (IACV rewired) and P2P ECU. The setup has run great for 4K miles, so this issue shouldn't have anything to do with install/wiring.

On my way home from work today, I came to a stop sign (luckily right in front of my house), put the clutch in, and the car died. Started right back up, and died. It runs with my foot on the gas, but it just immediately dies when not on the gas. It also seems to not run very smooth when lightly on the gas holding at low RPM, but when revving quickly, it seems perfect.

I tried disconnecting the battery to reset the ECU, and also unplugging the IAC and it changed nothing. There was always a CE code due to the P2P ecu and non-vtec head, so I don't know for sure if a new code was thrown when this happened. I may bite the bullet and buy a code scanner after work tomorrow.

I'm at kind of a loss at this point. Any ideas? Maybe ECU? MAP sensor?

fleabag

Assuming that your frankenstein setup isn't the cause, you should clean up your electrical grounds thoroughly all through the engine bay. Next step, do a fuel pump test to by turning the key and listening for the pump spin, make sure the pump sounds right. I'm very familiar with all the sounds my car makes so I know what a fuel pump should sound like. You might want to replace fuel filter if it's clogged. If you had an obd reading you could check like the tps output and what not to see if anything is messed up.

jjschafe

Update...

Pulled codes, and I was getting a 14, which is the IACV code.

So tonight I pulled the IACV off and soaked it in carb cleaner.

While I waited, I did two electrical tests, shown in the service manual here:


The first one, I got 12volts, but the second one I couldn't get anything. It's tough to get a jumper in the ecu connector to measure on, so I can't say 100% it is a problem, but I tried multiple times and ways and couldn't get anything. I checked all the wiring, and can't find anything that would be a short. Maybe the short is in the IACV?

I hooked everything back up, and no change, so the "gunky" IACV seems to not be the problem.

Other interesting finding - I started the engine (with foot on throttle) and revved it to keep it running for 15 seconds or so. There is a crack in the top of the exhaust manifold (always has been), and fuel was actually coming out of it... at an alarming rate. So, for some reason the ECU is DUMPING fuel in.

I also tried wiping out the throttle body, and also starting with the MAF unplugged. No change.

My only other thought is to buy a new IACV for way too much money, plug it in and see if it works. Any other ideas or things to check?

nub

The second test is with the ecu B connector unplugged. You don't have to test from the wire side. You should be able to use a straightened paper clip to probe the ecu side of the plug if your meters probe won't get in there.

If you can get the P code with a scanner it will be a lot more specific than jumping the service connector. Most auto parts store will do it for free.

fleabag

Soaking the IACV in Carburetor cleaner isn't enough. What you have to do is take it off, get a q-tip and try to manually actuate the IACV with your fingers. The IACV on these cars is like a half pipe cylinder that rotates around. Mine had completely frozen so I basically was able to break it free. From there, I then cleaned the face of the IACV, rotated it around so it sounded like it was rotating smoothly. This required a bit of work with a q-tip and rubbing alcohol but otherwise I got it spotlessly clean and afterwards not only did it fix my issue but it also fixed another issue I had with the car even before the IACV froze up.

As for the manifold, yeah my manifold is also cracked like a lot of these cars tend to and you will get that whiff of exhaust fumes especially if the manifold gets really hot. However you said you see fuel coming out of the manifold. Is it literally like liquid that is coming out? How do you know it's not condensation? If mean if you're having issues with the fuel injectors, then you'll need to have them taken off and professionally cleaned.

nub

What you're describing is a 3 wire (rotary) IACV, he has a 2 wire (plunger)which is different.
The 3 wire version can take a little more work to clean though as you pointed out.

jjschafe

Another update...

The car isn't throwing any codes now, which is just beyond strange. It is dumping in so much fuel that it cannot idle, yet the ECU doesn't see anything malfunctioning.

I've confirmed that the the TPS is giving good signals to the ECU (not stuck at WOT or anything). I still need to log the fuel trims to see what the injectors are doing.

I had someone suggest that maybe the fuel pressure regulator diaphragm failed and was pushing fuel out of the vaccuum hose, into the intake, and then flooding the cylinders. This seems like the most likely scenario, but I couldn't find any traces of fuel in the vacuum hoses.

fleabag

If you have a computer tool for the car, what you can do is put the tool in the windshield so you can see the real time information such as fuel trims, GPH, RPM, etc. Then put a vacuum hose on the fuel pressure regulator, and while the car is idling, suck on the FPR. You should see a change in how the car idles, fuel consumption, etc. etc. If no change, then either the FPR is bad AND OR you have something serious disconnected such as the MAP sensor which will cause the car to run @ its absolute richest condition which is like 2.62GPH which is obviously too much @ idle.

tlarimer

iTrader: (3)

Why are you using the P2P vtec ECU?

You should be using the P2E, since you have a D16Y7 and no vtec, surprised you're not throwing codes for VTEC solenoid

Are you using the Y7 injectors or Y8?

Try using a P2E ecu and Y7 injectors.

Also is the car auto or manual?

jjschafe

I tried logging while the car was running, and for some reason it shows Fuel Trim as 0. MAP looks correct, I think (98kPa before starting and then goes down after started). I can't do a lot while the car is running, because there is literally fuel spewing out of the exhaust manifold, onto the cat... so I only run it like 15 seconds at a time, for fear of fire.

I plan to do some more tests today on the FPR and injectors. Will report back.

The previous owner was planning to run a P28 in combination with the Y8 intake mani, so he did all the wiring for the 2 wire IACV. Then he sold it to me with the P2P instead of rewiring everything again. It does throw the VTEC code, but that is it. It is y8 intake mani and y8 injectors. It has run flawlessly for 4.5k miles. I double checked all of the 3 wire to 2 wire wiring, and it looks good, so I tend to think it is something that has failed, and not necessarily the parts setup.

Former User

1. Replace the P2P ECU with the proper P2E ECU.
2. Replace the cracked exhaust manifold, which is causing the ECU to dump massive amounts of fuel into the cylinders.
3. When ^these are done, drive your car to AutoZone to pull the ODB2 codes. There are two different OBD2 codes associated with OBD1 code 14. You need to know which one your ECU is throwing.

tlarimer

iTrader: (3)

Just because it ran "fine" for 4.5K miles, does not mean it ran right. You are using the wrong ecu, with the wrong fuel tables and timing for the engine you have, eventually something is going to give.

Set it up right and diagnose problems after that, only way you are going to solve this, unless you just want to start buying and throwing new parts at it hoping to get lucky for a while.

Is it auto or manual? This is an important question to answer regarding ECU

jjschafe

I now have an OBDII scanner (pulled the OBDI code 14 while I was waiting for my amazon shipment). The car no longer throws any IACV code. It must have either been an old code, or maybe it was just starting to get gunked up, and my cleaning helped it.


But... there is no "right" ECU for a D15b7 with D16y7 head and D16y8 intake manifold. I would guess that matching the P2P ECU with y8 injectors/fuel rail would be closest. Just a guess though. Not to dismiss your post... I'll probably start looking into tuneable ECU solutions for the future. Oh, and it is a Manual.

On a more positive note - I think I may have figured it out after trying a few things today...

I pulled the vac line off of the FPR. No change in running, and no fuel coming out of the vac opening. So, the failing FPR diaphragm theory is out.

Then I pulled the connector off of all injectors. With IG ON, I had 12v on one pin and 0v on the other for each harness. So, the ECU isn't "stuck" giving some crazy injector signal.

Last, I pulled injector harnesses one at a time, and tried to start the engine. 3 of them created a very obvious miss. Pulling the connector from the injector on the far left (whichever cylinder that is) didn't change anything. Still revved relatively smoothly with no "miss" of a cylinder being completely down. And gas still coming out of the cracked manifold So, I am pretty sure that injector is stuck open, and is going buck wild no matter what the ECU is telling it.

I have a reman injector that will be in at Advance Auto tomorrow morning. Will pop it in and report back.

Former User

You need a P2E ECU because it matches with the D16Y7 head.

You also don't grasp the fact that the fuel dumping is due to the cracked exhaust manifold.

tlarimer

iTrader: (3)

Typically the ECU and injectors should match the head, in your case D16Y7 head uses the P2E ECU. Y8 Intake manifold has nothing to do with it, I am running a Y8 auto intake manifold on my 99 D16Y7, Y7 injectors and P2E ecu.

The P2P ECU and Y8 injectors are designed for vtec and use/spray more fuel than your current setup requires.

jjschafe

So, you're saying that the crack in my manifold that has been there for quite some time (while getting 40mpg), is just now making the engine dump so much fuel that the car won't even run? Run rich? Yes. But not that rich.

Anyway... This morning I replaced the injector that I suspected was stuck. Car fired right up, and besides quite a lot of smoke out of the exhaust from the fuel that had dumped in, it seemed to run great. I shut it down and changed the oil (assuming some fuel had gotten in while that injector was going bananas). Started it back up and let it warm up. Everything seemed good, so I took it for a quick drive and logged some data. Everything looks pretty kosher... and the smoke is all but gone. Seems like problem solved.

Thanks to all who offered constructive comments. It never occurred to me that the ECU is better matched to the head than the injectors. I have a P2E ECU and y7 throttle body (with IACV) sitting around, so I will swap that soon. Also planning on patching the manifold crack (I had it patched before, but I think the ridiculous freezing temperatures this winter rendered the bonding useless). Eventually I'll replace it... this car is just my cheap winter beater.

Former User

You first quote clearly indicates a massive exhaust leak around the primary O2 sensor. This will cause the engine to run very rich. Perhaps the crack has widened over time, but it's currently a very concerning leak.


You could either have the crack welded or the header replaced.

fleabag

I think the better question is, what made you suspect a certain fuel injector to be the problem? (Obviously it was the issue, but what made you drawn to that injector specifically?)

mudko3

Another thing you may want to check is for vacuum leaks, last night on my del sol swap we ran into the same issue and was solved by leaving the nozzle where the purge sensor unplugged and it ran fine. also check for shorts in the system , make sure all grounds are grounded !

jjschafe

Stuck injector was always on my list of possible causes. After testing just about every other sensor and system I could think of, I just started pulling injector harnesses and trying to start the car with only 3 injectors connected, just to see what would happen. 3 of them all had the same effect - the engine clearly had a huge miss (while revving to keep it running). When I pulled the harness from the stuck injector, the car ran exactly the same as if I hadn't pulled the harness. My assumption was that the injector was stuck open, so whether it had voltage applied or not, it was just spraying continuously due to fuel pressure on it. Turns out I was right.

Blind squirrel and nut? A little...

fleabag

That makes sense, glad to read not only your response but also you fixing your issue.