Background: 93 cx hatch, swapped the d15b8 for a z6. The b8 did have some trouble starting and would stall out at red lights once warmed up. The donor was wrecked in the rear and I drove it back to the garage and ran smooth. Not a hiccup or a stutter. After the swap, and a little persuasion, got it to crank and start but the idle is rough and it wants to die. With throttle it wants to drop out. If it makes it through it will climb on the tach but once it levels with the throttle position it just fades down til it dies or the throttle is released.

Codes I'm getting are intake air temp sensor (don't know, don't think would cause this) and vtec spool solenoid (not wired up, not sure it would affect anything but vtec)

After the swap changed plugs (new ngk's), checked for vacuum leaks (none that I can find even with starter fluid), exhaust has a slight leak from the header to the straight-pipe (header and pipe not level), changed the fuel filter with the swap. Added a grounds to the valve cover and the block.

I will probably finish with ignition (wires, cap, rotor, coil) but it ran fine before the swap. I left the dizzy on when I pulled it and did not touch the timing but played with it a little tonight to see if it would smooth out. Did not have to seem much affect either retarding or advancing.

Had suggestions to look into the fuel system as that would be the only system that would be the same on the two motors. Maybe a clogged line or faulty fuel pump. Will be looking into it tomorrow.

Any input, thoughts, suggestions would be greatly appreciated. Just want my civic back on the road. Tired of hoofing it to work. Thanks for looking.

 

Well checked fuel all the way to the rail. Does not seem to be a clog anywhere. Pump primes solid all lines and the rail. Fuel doesn't look dirty at all.

Changed alternator and battery to see if maybe not getting the charge it needs. Seemed to help the idle but still dies when the throttle is held.

Didn't have a rubber glove to test the plugs on the valve cover. Took apart the dizzy, doesn't look corroded. I have definitely seen way worse run strong.

This seems like one of those issues that I could go by piece by piece and replace the entire ignition, fuel, air components and still may not solve the issue. Don't really want to go that route.

If anyone has any ideas on what to check for wiring, maybe a short somewhere or something. Wiring is completely foreign to me so any advise on where to start would help. Did start disconnecting anything not engine related. (radio, subs, tach) anything that looks like it was wired by the previous owner.

 

No change today.

Cleaned the injectors and replaced o-rings, checked wiring from the harness to the ECU based on the Chilton diagram. does not seem to be any problems that I can find. Checked grounds, zero resistance from the neg term to all the engine grounds. Still tearing apart the interior. Looks like the left overs of a security system. All the wires were cut so I just removed it, can't find a remnants of the system in the engine bay.

Probably going to throw new wire in tomorrow, price cap and rotor, have a new accel coil. Keep checking things.

Two questions:
How do I test that the pump is working properly when the car is running? It primes just fine but I've heard of them not holding the pressure when the car is running.

Would vtec not being wired up cause any of these issues?

Running out of ideas. Little help fellas?

 

Didn't get much done today, too much else going on in my life but I have been reading that the main relay can cause these kind of issues. Pulled it and checked for crusty solders but did see any really bad. Some orange/redish around some of the solder points and on the main board, here is a pic. Should I replace it?

 

When you took it out did it give a funny electrical burn like smell?

 

Not that I noticed. It still makes the click when the ignition is turned to ON>

 

You can wipe all that off with rubbing alcohol. Its just rosin from when they soldered your board. While you have it out, reflow all the welds, and that just might fix it. Whoever was soldering boards must have been the new guy, or they were drunk all the time, because its a common fail point. (tho, that pic, I only see one or two suspect solder joints, there could be more, hard to tell from one pic)

Fixed mine a while back. Make sure you have a good iron. A lil 10-15w one wont do squat. (or you hold it in place so long it burns up the component)

I used a 40w Weller, and even that took a while to get a flow going.

ALSO, do you have the IAC in the FITV, etc, etc.. I think they are close enough that its a common mistake.

The basics are air/fuel/compression/spark. Air might be one of the two above. Check spark with an old plug ground to the block, and tell us what color it is. If you get spark, then its compression test time.

I'd also be suspect of the old alarm system. Since you said the B was running rough too, maybe there is a ground problem in the ECU, Fuse panels, or harnesses too..

 

You mentioned above that you're getting cel code for air intake temp sensor & vtec solenoid(not wired up). Well, those won't affect the starting of the motor, but I would definitely replace the temp sensor and wire up the vtec solenoid. I've started motors without the vtec, O2 sensor, or map hooked up and starts without dying out, just the cel lights up. Have you switched out your ecu for the P28, since you mentioned that you swap it for a Z6? Also, you might want to check out the oil from the motor, if it's milky in color or the coolant in the radiator to see if it has some oil blobs floating around. You might have a blown head gasket from that Z6 motor you know.

 

Thanks for some stuff to check. All the sensors are correct, labeled them when the harness came off and have also swapped plugs on most to check if they did get mixed up. Going to swap the IAT tomorrow found an old manifold Had laying around. What about the O2 sensor. Kept the one on the Z6, is a 4 plug heated O2. The B8 only had a 1 wire O2. Do I need to wire the other three up? From what it looked like the in the Chilton Diagram they all ran back into the harness to other components or grounds.

Tonight I re-soldered the main relay. No change.

Tore all old non-honda wiring. (amp, subs, radio, tach, horn for autozone steering wheel, all old wires that look like they were part of the security system -looks like was sliced into the ignition wire then cut out and those two wires spliced back together- pretty much a clusterf*** of wires) reconnected any original wiring. No change.

Tested spark with newish plugs in all wires, looked pretty bright white, definitely not blue or orange. Got new NGK wires, cap, and rotor on the way with new ignition coil waiting to go in too. So even if ignition is the problem it won't be by the end of the week.

Yes I have changed over to the p28. Any chance the wiring harness in the cabin is different? Also tips on how to run down a bad ground to the ECU, fuses, or harness. Checked resistance on the valve cover, right around zero to just about anywhere on the chassis.

Also still kinda suspect the fuel pump because it is really the only common thread between the B and Z that has not been truly tested. It primes but I've heard that sometimes they don't keep the pressure. Also is the fuel return line at the tank suppose to actually flow back to the tank? was playing with it today and when I primed the line a few times no fuel flowed back through that line. Does it only return when the Intake has pressure?

Sorry to get long winded, I'm loosing my mind because the motor ran fine before the swap but now it I can't get it to run with any throttle. Just trying to talk this out and give you all every detail I have. Thanks for the help.

 

Check spark plugs to see if there not burnt out or no oil leaks. I found that I had a bad head gasket because it did the same with me.

 

Well, spark is good news.

Do what ^ said, but start the engine before, then pull plugs and see if they have gas on them after it dies. then, while they are out, do a compression test, just in case. that takes care of 3/4 things.

Not sure, but I think return lines should be open.. FSM (you need to get, or download) says frequent stalling is two things. BEFORE warm up, is IAC then "Other idle controls" then "other fuel supply" lol. AFTER warm up (does it ever warm up?) first is "Other fuel supply" then IAC.

So, change that IAC and lets see after that. (and compression test to be sure)

 

Had to much else going on to get any progress on the hatch.

Tomorrow I will be getting a compression tester and post the results. When I pulled the plugs to test them, they have a solid layer of carbon already. They were only replaced last Friday. Only been idling for a while since. Did not seem be soaked in fuel. I will check again.

As for the "warming up" question, it does warm up if I let it idle. It idles pretty smooth now, but when any amount of throttle is applied the rpm's drop right off.

Another thing I noticed but forgot to mention was the charcoal canister was removed and the lines have been capped. They have been capped solid and does not appear to have any vacuum leaks. Could this be causing the issue? Is the computer not picking some signal up?

Also jarvis what is FSM?

 

Shoulda just googled it first

FSM = Factory Service Manual

 

Well good news and bad news. Good news is I have good compression across the block. Bad news is (and I never thought I would say this is bad news) no blown head gasket. No oil in coolant or coolant in oil.

Still struggling to find any bad grounds or wire that were clipped, spliced, or otherwise messed with.Found one spot right above the hood release latch under the fuse panel that looks like it grounded something at one point but no dangling or cut wire were found. I did find that the positive terminal cable was pretty badly corroded. The wire itself was caked with corrosion so I'm going to replace that and the battery tomorrow. They both look pretty old.

Again I don't really know at this point. I've run out of troubleshooting steps. Don't have any idea where to go at this point. Any input, thought, idea, anything really at this point would help.

Any way to test the computer?

 

Thought you were going to try an IAC? (dont buy one yet)

Also check the FITV, per the FSM:

Cold engine, pull intake.
Start engine
put your finger over the lower port in the TB and make sure there is air flow with engine cold. If not, replace FITV.

Warm up engine till fan comes on. Check valve is closed now. If any suction felt, its leaking. check for air in coolant. If ok, replace FITV.

Best way to test ECU is also to swap with a known working one of the correct type for your engine. p28 for manual.

 

Check for swapped sensor connectors by verifying that connector wire colors match the sensor.

 

My bad, I did swap another IAC on with no change. I will test the FITV tonight.

All the sensors have the proper connectors per the wire colors in the chilton diagram.

For testing purposes I have tried swapping them around (map and tps, IAC and IAT, Emissions purge valve and IAT) all only making it worse. Unable to start or not idle.

The P28 was known good. It was in the donor car which I drove 30+ miles back to the garage.

 

You might consider posting pictures of your sensor so we can verify that you have correctly identified them.

I'm also not sure I have a clear idea about the symptoms. Can you explain in detail?

You also have CEL codes. Is there a reason you haven't cleared them?

 

I can start the car and it will idle. Sometimes it will die out while idling. Otherwise the idle has been smoothed out with everything I've done. When light throttle is applied I can get it to climb on the tach some (up to between 3 and 4k) when I try to hold that it will slowly drop on the tach and die. If the throttle is pressed too hard it will simply drop the rpms til it dies.

CELs are Intake air temp and vtec spool solenoid, the IAT hardware is stripped and I'm not sure the best way to wire vtec. Try to get it running, haven't done the proper research.

As for the sensors, I can post pictures but i'm sure I have them right. Not my first Honda. Or my second for that matter.

 

It's prudent to fix all the CEL codes.

If you don't have an IAT sensor, just buy one. Are the wires and connector fine?

I think there's only 2 or 3 VTEC wires, so that should be a simple fix.

I haven't read the entire thread. Have you checked the mechanical and ignition timings?

 

Thank you, RonJ. Everyone else, for these symptoms, this is always the FIRST thing you check. Dragging this guy along for a week without even mentioning it...

 

I will get on those 2 codes, have a new IAT but the hardware (screws) on the current one is stripped out. Wires and connectors looked good. Will try to get vtec wired as well. Like you said two wires should be no big deal.

Yeah mechanical timing looked good (Cam gear at TDC, line up pointer and groove on lower timing belt cover should line up with red mark on crank pulley correct)

And ignition timing was good before I pulled it, indexed dizzy. Will have to get my hands on a timing light to test for sure. Will try to do that tonight.

 

The red mark? There should be four marks. Three are grouped together, and the fourth is all by it's lonesome. That fourth is the one you should be lining up with the pointer on the plastics. In fact, the FSM says it's white.

Attachment 519501

 

Yes my mistake, I read the Chilton wrong, the red mark is for 16 BTDC for ignition timing. The mech timing with the cam pulley at TDC has the crank pulley on the white make away from the other 3.

Could not get the ignition time as now I can't get it to idle. Replaced the battery and cable as the battery was really old and the cables were badly corroded. No change. Checked all sensor connections again and referenced them with the Chilton diagram again. Still could not get the IAT off, may have to pull the mani again. Wired vtec cleard ecu and the code. Cleaned the FITV and Replaced the IAC with a cleaned one, no change.

Now it won't even idle. New ignition parts should be in on Monday. So I guess i'm to the point of metering every sensor to find a bad one.

 

Did you use a new gasket for the Mani?

But I ***-U-MEd (re above) the timing wasnt messed with, but yeah, check that. I think you can rent the light at the parts stores.