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I completed my engine (D16A6 replaced by SOHC ZC with intake from original engine) swap for my 91 CRX Si.
The engine fires and warms up. (seems to idle a little low, around 500 rpm; and maybe a little rougher than my D16A6. But, the guy I bought the ZC from said he put a bisimoto cam for a little more performance.)
Once it’s warmed up, it will die at idle and won’t fire without giving it gas.
Things I’m currently looking at:
- vacuum leak (new 3.5mm tubing and 12mm flex socket to retorque the intake manifold are “in transit” here 4/27)
- maybe, a problem with charcoal canister
- the electric fan on the radiator has never worked (the fan motor is good); probably the fan relay near the battery
Other info:
the previous D16A6 ran like a top.
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Replies
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The charcoal canister has nothing to do with it I’m sure so you can tick that off the list. As for the fan motor you need to make sure you don’t have any air in the cooling system, in fact with a Honda idle problem the first thing to check is for air in the cooling system as this will offset just about everything including the cooling fan operation. I was just going to post a link to the video I did on bleeding a cooling system but perhaps the ‘idle speech’ might be more appropriate.
By suggestion I’m going to post my idle speech along with a couple of video links that I hope will help if your having problems with your Honda’s idle. First I’ll give you the link to the Solving Honda Idle Problems video, please remember that adjusting the FITV is the LAST step in the process and you need to back it off at least 1/2 turn after it bottoms out or it will not start properly when cold.http://www.youtube.com/watch?v=L788jKEVblYThe Bleeding a Cooling System Videohttp://www.youtube.com/watch?v=zUp … =relmfuThe video response to the Honda Idle videohttp://www.youtube.com/watch?v=AMj … onseLastly here is the “Idle Speech”There are a lot of things that can contribute to an idle issue, in fact in the end it may still be there to some degree because of the nature of a 4 cylinder engine however here are some things to start with.First start with a good tune up, use NGK or Nippon Denso plugs, don’t change the wires if they are OE, if they aren’t OE you might consider NGK wires as they are very good and less expensive then OE. A quality cap and rotor should be good. A new air filter also helps.Don’t change the PCV valve, if you see an aftermarket PCV valve in there put a Honda in, believe it or not I’ve seen idle issues caused by aftermarket PCV valves, the OE’s last just about forever so you can easily justify the expense.Next a good valve adjustment, this goes a long way to smooth out the idle if done correctly, mess it up and things can get a lot worse though.While you have the valve cover off check the timing belt tension, if you feel a lot of slack this can cause the cam to ‘chunk’ as it spins causing a rough idle. If you think the belt has been on there for some time then you might consider changing it and resetting the tension properly, if it’s not ready for replacement you can reset the tension to take up the slack.DO NOT adjust the idle screw under any circumstances, it is set at the factory and that is the reason it was sealed in the first place. If you find that the seal has been broken and you have a low idle and you have done all of the above then you might turn the screw out a little to see if that helps the idle but only enough to try and bring it back to where it was before it was adjusted in the first place.Last clean the screen in the Idle Air Control valve, this can get clogged up with carbon over time and cause the flow through it to be restricted which can cause idle issues.If you still have a ‘rough’ idle after all of this THEN look to the engine mounts as you want to be sure the engine is running correctly before you go for those as the one in the back is a real pain to replace.I hope this info is helpful as I get a TON of questions about Honda idle problems, thanks for reading.Hi Eric,
I watched your How to Fill your coolant system video (purging air from the system).My 91 CRX Si doesn’t have a bleeder bolt on the throttle body/IAC valve loop.
But, with the thermostat closed when the engine is cold, there should be plenty of coolant flow to clear any air out of throttle body/IAC valve loop and heater core loop. (almost the entire flow volume from the water pump would be shunted to those two loops with the radiator loop blocked by the closed thermostat).
Any air in the system should be flushed toward the upper radiator hose connection where my cooling system bleeder bolt is located.The PCV is a cheap aftermarket one. (I’ll replace it with OEM Honda PCV).
Plugs are currently Bosch Platinum, two ground arms pregapped. (they worked really well with my old D16A6.)
Air filter replacement is no problem.
I retensioned the timing belt per the factory manual when I did my sync check between the crank and the cam shaft. The timing belt is new.
I’ll check valve clearances this weekend (that’s a easy job I’ve done many times.)
Engine mounts were replaced as part of the swap (HASport EFSTK 62A polyurethane; the softest they make; the back mount was a piece of cake with the engine out.)
I’ll clean at the IAC valve intake screen also. (I looked at the one that came on the ZC’s intake its screen was carbon caked.)Other info:
My Fast Idle valve has a two-wire electrical connection, no coolant lines connected to it, and a spring inside instead of the plastic housing you screwed back down in your Idle video.Another idea:
Maybe, the fan switch on the back of the ZC is working correctly. (assuming the one on my D16A6 was bad and the fan relay is bad) But, the ECU sees that switch activate but doesn’t see radiator’s electric cooling fan kick in and cuts back fuel to the injectors to be safe?I’ll work on the car this weekend and get back to you.
Thanks,
ChrisYou do not need a bleeder valve to bleed a cooling system. Eric has stated many times that he wished he added that statement to the video.
As for cooling fan operation, you would need to look at a wiring diagram to see how that system works.
Keep us posted though.
Update:
I cleaned the IAC valve screen (lots of carbon).
Engine started and warmed to operating temp.
Checked timing (a little bit off); adjusted to correct specification.Result:
engine continues to idle when warmed up.
(still a little low, a tiny bit of surging maybe 500rpm to 600rpm)I have to do some driving to get the ECU trained on how the new engine behaves.
(that might be part of my overall problem)
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Further info, after test drive:
The car can still stall at idle.
Other than that the new engine seems to be running very well.
Air filter was replaced with a new one.
The ECU seems to be learning a little bit.I’ll look at valve clearances next.
Retorque the intake manifold (in three equal steps radiating out from lower-center bolt); still waiting on a 12mm crowfoot. So, this might happen some time next week.
3.5mm vacuum tubing is still “in transit” shipped on the 4/27.I’m thinking of replacing the bistmoto cam with the one from my old D16A6. (maybe, that’s what’s wacking my ECU’s thought process; I’ll wait until I’ve fixed the possible vacuum leaks before doing that.)
Take Care,
ChrisIs sounds like you are on the right track. I wouldn’t think that would effect the idle so much, but I’m not a fan of shaving the head to up compression. What grade of gas are you running out of curiosity?
Regular unleaded 87 octane.
I haven’t heard any pinging.(I’m also not a fan of raising compression either by shaving the head or carbon buildup on head & top of pistons).
Get some NGK plugs installed. lol
Is the igniter going or stressed at full temp/heat soaked? Is the main relay not flaking out once hot? How about any measurements of fuel pressure, just to check off at least?
I’ve heard of IACV going bad without throwing a code, if you could find a vacuum leak go for it.
Someone I’ve spoken with with a 92 D15Z1 like mine, had a consistent stalling problem on the same route/location traveled often. I believe the igniter was the problem, they may have even thrown in a new computer as well but that wasn’t related to the stalling issue, IIRC.
Retorqued intake manifold using 12mm 6pt flex socket, 3″ extension, and inch-pound torque wrench; three equal rounds: 68, 136, and 204 in-lbs; final = 17 ft-lbs. per factory spec for the intake.
(note: had to pull fuel rail and move clutch cable, throttle cable, PCV valve & hose for access.)Warmed up, check and adjusted ignition timing.
(maybe, one more timing check to do with “kill ECU adjustment” jumper in place; blue unconnected 2-wire plug near passenger door hinge.)Basically, it looks like the problem is solved.
Now, I have to tweak the throttle cable slack a little bit (it’s actually idling a little high now; factory spec is 10-12mm deflection; a simple one wrench fix).hbvx:
-the current platinum plugs are working fine (and have been for over a year.)
-the distributor was replaced last year (haven’t had any problems with that since)
-main relay was resoldered a few years ago (to fix the flaking out problem in hot weather; no problems since then)
-fuel pressure (I don’t have a guage for that.)
-there were no codes thrown at any time after I completed the engine swap. (or when my distributor went out last year. Not sure if it was the coil or ignitor.)Adjusted valve clearances. (0.007-0.009 intake, 0.009-0.011 exhaust; each cylinder’s valves were adjusted at TDC compression stroke for that cylinder)
On the drive in to work, the car stalled a couple of times at low idle. (Not a huge problem. But, annoying; sometimes the ECU keeps the idle up correctly.)
Probably, chasing a vacuum leak.
Low RPMs show it more because there’s less vacuum than at higher RPMs.
(should be able to fix everything this week; 3.5mm tubing shipped today, still waiting on 12mm crowfoot)Other questions:
-the guy who rebuilt the engine said he had the head shaved down 0.015 instead of the minimum to achieve flatness to raise the compression slightly.
How would this affect idle?Take Care,
Chris^Cools. I think it’s worth it to recheck the timing with the ECU test pins jumpered. I know that’s the recommended method on the 92-95 range models.
Yeah, I don’t think the plugs would cause stalling. However, there is some irony in me saying that as the lean-burn model I’m driving will near stall at highway speed; in gear, using Bosch plugs(there have been numerous experiences) because of the heat-range discrepancy among other things such as the lean-burn function.
You replaced the entire dizzy, right? OE parts or aftermarket? It ‘could’ be part of the problem if things resurface, I know eric recommends OE. Just sayin’, anyway. 🙂
Thanks for the reply. However, Platinum plugs are a gimmick in a ‘sense’. It’s all copper core for every spark plug anyway, it is the best conductor of electricity. You may just get longer life out of the platinum tip. Unless you are tuning, eh? ..and no I’m not Canadian.
lol
So, unless you are tuning I’d still recommend getting some good ‘ole NGK V-Power plugs back in or w/e the book recommends. gah…I suppose it doesn’t matter anyway. I just like being able to replace my plugs once every 2 years for under $9 and see the conditions of each cylinder. T)
If you had stalling problems while driving again, I’d imagine fuel delivery issues if not ignition related. That is why the suggestion for now to just see where you pressure is since you’re all swappin’ engines anyway. Might just want to ‘swap’ the fuel filter.
bhvx:
-you might want to look at your O2 sensor(s) when they fail/go bad they cause the ECU to lean the mixture way out. (that’s what happened with my CRX)
-the bosch platinum plugs have been very good for me (correct heat range and the platinum electrode is very wear resistant compared to a standard plug’s electrode, also allows for more precise spark since the platinum electrode is a much smaller target)
-my distributor is aftermarket. (OE would be nice; but, it’s basically twice the price. I check before I bought.)
-my swap ZC replacing D16A6 doesn’t even need to BAR’d
the engines are mechanically the same assuming you use the old intake and exhaust which I did. If I moved to a B16 DOHC that’s a different story and not one I’m interested in. My CRX Si is plenty zippy; faster than many people realize. The only modifications I’ve done are put a Stage 1 Excedy clutch and pressure plate in (grabs fast and very driveable) and HASport EFSTK 62A motor mounts.Quoted From Chris95118:
bhvx:
-you might want to look at your O2 sensor(s) when they fail/go bad they cause the ECU to lean the mixture way out. (that’s what happened with my CRX)
-the bosch platinum plugs have been very good for me (correct heat range and the platinum electrode is very wear resistant compared to a standard plug’s electrode, also allows for more precise spark since the platinum electrode is a much smaller target)
-my distributor is aftermarket. (OE would be nice; but, it’s basically twice the price. I check before I bought.)
-my swap ZC replacing D16A6 doesn’t even need to BAR’d
the engines are mechanically the same assuming you use the old intake and exhaust which I did. If I moved to a B16 DOHC that’s a different story and not one I’m interested in. My CRX Si is plenty zippy; faster than many people realize. The only modifications I’ve done are put a Stage 1 Excedy clutch and pressure plate in (grabs fast and very driveable) and HASport EFSTK 62A motor mounts.I’m not saying this is causing your problem but Bosch plugs don’t belong in that engine and the aftermarket distributor WILL cause problems just check through the forums here and you’ll see how many people are having problems with them.
In the end I’m thinking someone either messed with the idle screw and doesn’t have it adjusted correctly or you may have a problem with the IAC. BTW it should NEVER be adjusted.
Lastly I don’t think you followed the proper procedure for bleeding out the cooling system as the bleeder valve has nothing to do with purging the air from the system it’s only there to make filling the system easier you need to follow ALL of the steps in the video in order to be successful at bleeding all the air from the system. Also you don’t need the funnel just put a pan under the front of the vehicle to catch any antifreeze that may boil out.
Eric,
I’ve had no problems with the Bosch Platinum plugs (they’ve been in the car for over a year).
I sent you a picture of my distributor. I think it’s a rebuilt OEM.The idle adjustment screw is still sealed with epoxy. (it wasn’t adjusted.)
After I got home tonight and the car cooled for about 20 minutes, I felt the bottom of the IAC Valve and the tubing in that loop. It was hot meaning coolant was running through it. Pulled the radiator cap. Full to the top of the neck. Squished the top radiator hose by hand. No air, just coolant.
I think I might have an electrical problem.
I had I bypass installed from the positive battery clamp to the main positive connection in the engine fuse box because I suspected that line was not up to snuff. I removed it and reconnected the factory lead that’s integrated in to the positive battery clamp.
Result: car won’t idle.So, I have to order a couple of things from my Honda OEM parts supplier.
-ground cable
-positive cable
-PCV valveProbably should have the battery tested also. It’s almost 5 years old.
Hopefully, that nails it.
Take Care,
Chris
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