Putzman02

Ok, I'm going to try to be as thorough as possible here, so all the basics get covered. I have a 97 HX coupe with a 94 D16Z6 swapped in. I am running the P28 that came out of the same car as the engine, with a conversion harness. The only wiring modifications I made were splicing the distributor harness from the HX dizzy to the D16Z6 dizzy, soldered and heatshrinked, and depinning and repinning the HX secondary O2 sensor plug to the primary location so I didn't have to cut the HX harness up. After I got the engine dropped in, it fired up and ran almost perfect. The only problems were it had the gangster idle, it ran cold, and it had a little cutting out problem in between dead cold start and getting to operating temp. I solved the gangster idle and running cold issues with a new thermostat as the one in it was stuck open. At the same time I replaced the thermostat, I put the stock exhaust manifold/cat back on because the header I put on hung way too low. Ever since then, the cutting out has gotten way worse. From a cold start, it idles and runs like a top, but after 2-3 miles it bogs down while cruising. If I let off the throttle, it snaps back to normal, and if I give it about 75% throttle it picks back up like cracking VTEC on a built B series. It acts like its either starved for air or fuel, lots of bucking and backfiring. The plugs, cap, rotor, wires, air and fuel filter are all new. I pulled the injectors and cleaned the screens and tips on them and threw them back in with new seals. I cleaned the PCV valve. I swapped on a known good fuel pressure regulator. I changed the O2 sensor with a known good one. I cleaned the IACV. There isn't an FITV as I used the HX throttle body. The TPS is .5v-4.5v. The coil is .7 ohms and 16,000 ohms. The ICM, so I have heard, is either good or not and it runs so I'm assuming its ok. The MAP worked on the D16Y5 just fine. The main relay has never given me any problems, the fuel pump always primes. Valve lash has been adjusted and checked twice. Mechanical timing is dead on, ignition is @ 16 degrees BTDC. Compression is good and even across all 4. I've noticed the dash lights have been dimming a little lately but the alternator bench tested good 3 times so it just seems like the common ELD oddity. Battery is only a year old and holds its charge. I am completely stumped. Can anyone see anything I could have missed or have a solution to this cutting out problem? Thanks in advance!! Sorry about the long winded post, but if you read it all the way through, you will have seen my problem AND everything I've done to try and fix it.

RoidBear

You've done quit a bit already to troubleshoot the problem, so thank you for explaining all of that. That'll save everyone alot of time trying to figure out what is going on and what you have done.

Have you checked your throttle cable adjustment yet? When I swapped out my Z6 intake manifold for the Y8 mani, I had to play with the throttle cable adjustment quite a bit before I could get the car to warm up right and idle without shaking as if it needed more gas or air. Try playing with your throttle cable adjustment nuts on your intake mani and see if that makes a difference on how it idles and how it responds when you're driving around. You should feel how your car reacts after driving it for a couple of miles of stopping and going traffic.

I hope you find the problem soon!

Putzman02

I had to do a lot of adjusting and tweaking to get the throttle cable to fit the Z6 intake manifold already. I'm fairly confident its as good as it will get. I just got done bangin my head on the wall a little more though. My positive battery terminal was broken and the plug gaps were WAY too big. I have always been under the impression that NGKs with the cardboard sleeves are supposed to come with the gaps set already. Stupid me for not checking before I threw them in. I also threw in a different MAP sensor thinking maybe the old HX one randomy died. Still no change. I drove around for a few minutes and it still cuts out bad. It literally feels like the more I push on the pedal, the harder it bogs... until I get about 3/4 throttle and then it snaps back like a bat outta hell. I got home and tested the coil again, ahhhh. Primary was down to .35 ohms. Secondary was still a little over 16k. BUT, I have heard that you're supposed to test the coil at or around 70 degrees F ambient temp. Would being tested right after being driven affect the readings that much? I had a Toyota 4x4 that I put a 350 Chev small block in and the MSD coil would heat up after a few minutes of running until I put a ballast resistor in. When that coil heated up, the truck started cutting out too. So I'm curious if my current problem is similar, once the coil gets warm, it doesn't function properly.. The only thing keeping me from going out and spending $75 for a coil is the uncertainty about testing temps vs readings and the fact that after a certain amount of throttle it comes back to life. Should I just bite it and buy a new coil?

Putzman02

Small update! I decided to recheck everything and reroute some wires and cooling lines. I let it sit and idle to bleed the cooling system again and it seemed to be idling a little low. I turned the idle adjustment screw on the top of throttle body almost all the way out before it changed and it seemed to idle a lot smoother and a little higher. I took it for a drive around town and no problems whatsoever. I stopped at the store and left about 10 minutes later and still no problem with cutting out. I got within a block of my house and it fell back on its face. The problem came back with a vengeance. I drove around the block a few times to make sure it wasn't a fluke, which it wasn't, and when I parked and got out it smelled hot as @#%&. So, either it's starved for fuel and running lean, or it's losing spark and the cat is being overworked trying to burn off the unburnt fuel. Anyone wanna buy an EK coupe ?

Former User

1) I think you should install a D16Z6 throttle body.

2) Any CEL codes? Does the CEL work?

3) Is fuse 15 blown? Is the alternator belt tight?

Putzman02

I'll try the Z6 throttle body and check fuse 15 when I get home. The alternator belt is tight. And no CELs and the light comes on when you first turn the key. I noticed when I was driving it last night that the dash lights dimmed when I was on the gas and got brighter when I let off. You think this might be related to the bogging issue? And is it normal for a coil to read different when the engine is at operating temp?

Putzman02

Ok, Z6 throttle body didn't change anything. Fuse 15 is good. The Ignition 40 amp fuse under the hood looked a little corroded inside, so I changed that. I tested the coil for the 10th time, and couldn't get a consistent reading, so I cleaned the wire connections on it and it tested good again. Took it for a drive and it was a little better, but still bogged down. Stopped at the store and a wild hair told me to unplug the vacuum line on the FPR. After 10 miles of cruising, not a single stumble. Idle is a little rough, but other than that its perfect. I'm gonna pull the fuel pump and see what the strainer looks like and blow out the lines. Anything else to look for? Correct me if I'm wrong, unplugging the vacuum line on the FPR should, in theory, bring up the fuel pressure. If it runs good with it unplugged, something is causing lower than normal pressure to begin with, right? I'd rent a pressure test kit but the parts store said they only have 1 and someone else has it.

Putzman02

Any other suggestions? Fuel pump screen looks brand new even with 200k+ miles. And just like clockwork, the problem is back. Not quite as bad, it picks back up a little quicker, but its still doin it. Someone has to have experienced this AND solved it.

Jgreen94

iTrader: (1)

Any luck? I'm having this issue with my stock 97 dx. It's so frustrating any help would be appreciated.

Putzman02

What all have you tested or replaced?

roryss024

iTrader: (1)

iv been having a similair problem with my 98 ex with a y7/y8 head swap, acting the same with stuttering/bogging and being starved of fuel/air. im throwing code p0450 though, which im gonna look into this weekend now that i have some time. anyways if your still having it and outta ideas may wanna take a look at the purge solonoid or canister. do you have a haynes or chilton?

12340987

Looks like we are in similar situations. My 98 EX 5spd cpe has a z6 block and and a y7 head, I think, done by the previous owner. It also has a pretty ghetto looking intake. It has a very frustrating throttle flutter that starts around 1500. Adding throttle at that point makes the fluttering worse. I'd say it wavers by about 100 RPM very rapidly, so the car bucks when you are in that RPM range. If you press on the pedal more it shoots up way past 2000RPM, but it is smooth. You can never really get it between 1500-2000. Makes it very irritating to drive.

I just replaced the TPS and there has been no change. When I cleaned out the IACV I think it actually made it worse. If I disconnect the IACV it makes no difference. I also cleaned up the TB. Putzman: have you backed out the idle screw and cleaned it up that way?

One thing that concerns me: The sensors in the block are not right for the ECU, could that be the problem? I'm wondering if I should change the CTS and thermostat to match one for a 98, because I know the thermostat in the Z6 are 10 degrees cooler than what you would find in a 98 ex. Would running a hotter tstat kill the engine? I'm thinking something isn't happening during open loop like it should it all our cases.

Josh Grindstaff

Soooooo I have the exact same problem, I have a cel, but someone hacked the harness so it wont read (pulling my effin hair out). I was almost excited when you pulled the vac off the fpr and it did better. Did a new fpr do the trick ????

Steven Aldridge

same issue as well with my 93 runs worse in time than it does 1 tooth advanced but cuts out ...in time cuts out at low rpms out of time cuts out at hight rpms