D16Frustrated

Hi guys,

I wonder if the ghuru's or those with experience can help me with a problem that's driving me INSANE! This relates to a Honda HR-V, but it is a Civic engine in the car - and to be frank, I'll try anything to get to the bottom of the problem.

Right, the background - An engine swap was required on the car due to No 4 con-rod exiting through the sump due to lack of oil - not caused by me. A replacement D16W1 engine was put in with new belts (including timing with new tensioner) new oil, filter and fuel filter. The crank sensor from the original engine, together with all sensors and dizzy were also transferred to the new engine before being refitted.

The only sensor that was not brought across was the exhaust gas sensor as the new engine had an uncracked exhaust manifold. The original inlet manifold, injectors, and throttle body were also transferred across.

Once completed, the engine was cracked over with plugs out to get oil pressure and then started. Started on the button no problem, but revs went straight to 3k rpm for approx 10 - 15 seconds before dropping to 1500 rpm and then bouncing regular as a metronome between 1500 rpm and 2500 rpm every 2 seconds.

This continues irrespective of the engine temperature as I have left the car to run through at least 2 cycles of cooling fan coming on.

Steps taken

1. No fault codes on ECU
2. TPS checked for correct voltage at open and closed throttle.
3. IACV checked for correct voltage
4. Air and water temp sensors checked for correct reading.
5. Continuity of wiring checked
6. ECU Reset and backup fuse removed
7. Throttle body removed and cleaned

Car was taken to a Honda dealer and plugged into their diagnostics machine and returned no faults, but idle was still the same. Their suggestion was either timing or IACV.

Timing was then checked and found to be correct. 2nd hand IACV sourced and fitted - no change

New TPS sensor fitted - no changed.

Original IACV put back on the car and after reading through this website, I took the throttle body off again and cleaned it. FITV as pictured in the guide is part of the IACV so this was stripped and found to be cleaned.

Adjusting this makes no difference to the problem.

Sprayed wd40 over and around the inlet manifold - no change to idle.

I will try the idle screw on the TB to see if this makes any difference at all, but I'm seriously running out of ideas here - does anyone have any suggestions or pointers I can look at?

Part of the problem is that I don't know the car as it was before the engine swap to be absolutely certain the problem wasn't there before, which is equally frustrating! Anyhoo, over to you guys!

Former User

What Civic engine?

D16Frustrated

It's a D16W1 engine or basically a 1.6, 16 valve, non-vitec motor

Cheers

Darren

EGgmannate81

I have seen this problem several times and we always clean the IAC and adjust the Fast Idle and if that doesnt work then we check the wiring and have found a bad pin in the plug that goes to the IACV a couple of different times. So check the wiring and go from there. Im not sure but I have read on here that you could have air in the cooling system and this could cause the IAC to act up. Correct me if Im wrong.

D16Frustrated

Thanks for that - I'll check the pins and see if there's anything to see. I'll check for airlocks in the system, but I think I already did that - in fact I definitely remember coolant in the IACV when I changed it over again last night.

Cheers and will let you know how I get on.

Darren

D16Frustrated

OMG this is a busy forum - 10 pages back in less than a week, phew!

Anyway, took the car out for a good run at the weekend and no change to the problem. Checked the connectors and they all look ok - is there anything in particular I should be looking for?

A couple of observations, which may or may not be relevant.

1. The bouncing on revs from 1500 - 2500 rpm is regular, like clockwork.

2. It's almost as though the engine is falling to stall and then being picked up again to 2500, like revs are rising to a peak at 2500, then engine cut til they drop to 1500, - engine back on again to 2500. No dash/warning lights though so it's not actually cutting out.

Any other thoughts guys?

Cheers

Darren

creationz

I would check the coolant level. I had the same issue with the same motor. Changed all the sensors and checked all wiring with no code no problems but still bouncing idle. Find out after about 2 weeks of messing with it that there was air in the coolant system causing it to jump. Pulled the radiator cap and ran the motor and added water to the system as it ran. It bubbled and glugged but once I filled it to the max the idle returned to normal and have not had any issues since. Just something to check hope it works out for you. Good luck.

D16Frustrated

Thanks for the pointer - I thought I had checked the coolant level as there was coolant in the IACV when I last took it off, but I will run through the process of purging air and let you know. Fingers crossed that solves it, or failing that I am at a loss.

Cheers

Darren

D16Frustrated

Hi CreationZ,

Tried out purging the coolant system of air - heater on to hot, car on a slope, nose at highest point. Rad cap off and car run for several (ie more than 5) heat cycles of cooling fan cutting in an out. No appreciative 'glug' or expulsion of air. Cap replaced and header topped up - no change.

have checked the wiring as far as I am able and all have continuity, and even tried wiggling the wires with engine running - no change. Exactly what am I looking for in the connections/pins?

One question - and this shows the levels I am reaching - is it possible to run the car with the distributor 180 degrees out? The car runs fine off idle and drives no problem, but as I preseum it's a wasted spark, it may still run if it's out of whack. Obviously I don't want to just try it without any input from you guys, so anyone got any comments?

Cheers

Darren

D16Frustrated

Anyone?

flush_EJ1

Have you checked the O2 sensor. The idle will follow a lazy O2 sensor. I know you said you replaced the IACV but what happens when you unplug it and let the car run?

D16Frustrated

Hi there - O2 sensor is one thing not changed tbh. Unplugging IACV has no real effect to revs, they still fluctuate. Was wondering if 2nd and IACV was also faulty, but will look at O2 sensor.

Thanks for the tip!

Cheers

Darren

D16Frustrated

This damn car is playing with me! Right, to bring you guys up to speed.

I gave the car back to my friend to use and see if they can get used to the idling in the meantime. I get a call the following day to say the engine check light came on - wtf! Anyway, went over and started the car - idling steady at 1200 rpm on startup. Waited for the inevitable rev bounce and....nothing! Ran steady at that level through warmup cycle. blipped throttle and got a slight increase to 1500 and slow fall back to 1200. Engine light on.

Got CEL code 67 - CAT not up to par. Cleared this, restarted and back to rev bounce!! Unplugged O2 sensor on manifold - no change! I am going to add an injector and cat cleaner, and have returned the IACV for a replacement unit to see if that's it, because I can't see that it's anything else, unless maybe the CAT? It has 2 sensors in it, but other than this CEL code, nothing has shown up as a problem.

I'm wondering if this car's posssessed!

Comments gratefully received.

Cheers

Darren

shogee

Sounds like a vacuum leak, check all vacuum hoses to see if any are cracked or hooked up wrong. Then u can also check if the throttle blade is adjusted right by plugging the hole next to blade with ur finger, with the intake off obviously, it should idle around 4-500 rpm. If not adjust the idle stop screw, but if u mess with that then u gotta mess with the tps adjustment.

shogee

Engine wont run if its 180 off, itll backfire into the intake

D16Frustrated

Hi Shogee,

As it happens, you can't fit the rotor arm 180 degrees out anyway, but as it's not backfiring, then I assume it's ok. Thanks for confirming that it wouldn't run properly.

Cheers

Darren

D16Frustrated

Hi Shogee,

Afaik, there are very few vacuum lines. Brake servo obviously is larger than the rest. Fuel pressure regulator I think has another and the only other one runs through an electrically controlled valve, whose function I can't remember right now but unplugging the connector makes no change. I will check though and report back.

Brake cleaner spray around manifold and tb joints had no effect though.

Cheers

Darren

shogee

I dont think the brake cleaner method would work on a speed/density type car because the map sensor is already going to adjust for the vacuum leak by increasing fuel injector pulse, works on engines with maf's.

D16Frustrated

Thanks Shogee - I'll check, but are there any other ways of checking for a leak? I was careful when the inlet manifold was refitted and ditto with the throttle body, both gaskets in good condition.

Cheers

Darren

shogee

The im could be cracked, the easiest way would be to block off the tb with ur hand and it should kill

D16Frustrated

Hi Shogee - already tried that - nearly sucked my whole hand in! Certainly didn't feel as if there were any leaks! You can see why this is driving me up the wall! A new IACV is on it's way, or at least another 2ndhand one, so we'll have to see if that makes any difference.

Cheers

Darren

shogee

a couple other things to do is, with the intake off the tb, there is a hole on the inside of the bore of the tb, unplug the iacv and block the hole with ur thumb, and the idle should drop to 6-700rpm, if not too much air is getting by the throttle blade, and stop screw needs to be readjusted. Also u can pinch off pvc vacuum hose and brake booster hose one by one with the iacv unplugged to see if any changes occur

shogee

Did the engine kill?

D16Frustrated

Thanks for the tips Shogee, I'll give them a try and let you know.

Cheers

Darren

D16Frustrated

Do you mean did it stall? No, I didn't as I didn't leave my hand there - does it make a difference?

Cheers

Darren