1988 Civic Automatic. Stock. DPFI.

Replaced motor and was running pretty well. Took on long trip but it's misfiring at idle more and more. It stumble at first when accelerating from idle then pulls fine after. Also doesn't seem to misfire or stumble when going faster than just idling. Doesn't stall out. Starts right up.

All I did was put the motor in. Didn't do anything else other than set idle and timing. It had been doing this before the engine swap.

1) Used d15b2
2) No Check engine
3) Fairly new spark plug wires (8k miles on them)
4) Spark plugs that came with motor. I didn't check them.
5) Haven't adjusted valves.
6) Same timing belt that came on the motor.

What would be a good place to start checking for problems?

 

Going to start by replacing O2 sensor. It's not the original and a Universal Denso is only $14 at Autozone. The only other post I was able to find with a similar problem, they found it to be the O2 sensor.

I'll also be replacing thermostat. I'm pretty sure the motor I dropped in the car doesn't have a thermostat. It takes too long to warm up to operating temperature.

 

check your plugs, see if any of them are bad. maybe you have some bad gas in it. run some fuel injector treatment through your gastank/engine, maybe you drove the car low on gas and sucked up some crud.

 

I will be looking at the spark plugs tomorrow morning.

Once I replaced the O2 sensor the car was running great almost perfect. No misfire at idle. But the more I drove it, the more it started to misfire at idle. I notice it when it's cold and when it's operating temperature.

I also notice that after disconnecting and reconnecting the battery, the car runs great for a while. Then it'll start misfiring at idle again.

 

I found this thread because I have a similar problem with my 1990 Si so I am searching the site for solutions. My problem seems to be intermittent like yours. It always starts right up sometimes it has the problem sometimes it doesn't. Last night it was worse than usual and today it is running flawlessly. I will be following this thread and if I find a solution to my problem I will post it here.

 

ive had the same problem with my 89 hatch with d16a1 swap and all research and corresponding CEL code leads me to believe that it is my distributor. It may sound a little loopy but my misfire seems to happen more often or be more server under really wet and humid conditions. It almost always hard starts ei: 2-3 turns of key to start. Depending on when the engine was built it may or may not have a tdc sensor in the distributor. 1988-1991 they used two diff types of distributor systems which i might be wrong but is why i get a cel code and you do not. All IMO

 

I have yet to find the cause of the issue. I'm going to look at the following soon.

1) Spark Plugs,
2) TPS voltage
3) Thermostat? - I noticed that the car ran a lot better when it warmed up around here.

 

In my case it appears the problem was the ICU (Ignitor) I bought a cheap one off of ebay (item # 121338094594) $11.50 and I am on my second tank of gas since the replacement and the problem has not recurred. My car has a 1.6 so you might need a slightly different part if you want to test this solution.

 

Replaced spark plugs. Man were they in bad shape. Car ran better for a good while but still stumbled a bit. TPS voltage a bit off. I replaced ignitor and cleaned IACV and repositioned TPS at same time. Stopped stumbling when accelerating and misfiring at idle. Had ignitor checked after at Vatozone and they said it was still good. Saving that in the glove box. My guess problem was a combo of dirty IACV and TPS position.

I will keep updated. Sometimes problems go away for a few weeks then come right back.

 

I am having this issue again.

ICU died on me so I put the old one back in. Stumbling and misfiring at idle. Bought a new ICU at rock auto. Still doing same. Tried a different distributor. Not idling properly still.

I'm stuck. I wonder if I set the idle too low or if the IACV is bad.

I set idle at 650rpm with IACV unplugged. Once plugged back in, the RPM's jump to 750.

1.5L D15B DPFI
Automatic Transmission

 

I replaced thermostat and bled coolant today. Temperature gauge now stays constant when at temperature. It ran fine for a while but only for ten or twenty miles. Then it would surge every once in a while at a red light and misfire as well.

Still no codes. My guess failed IACV or another vacuum leak.

Anyone in AZ that can help me diagnose this? I'm stuck and I don't have the money to be swapping parts until I find the solution.

 

Sounds like your timing is off.

 

I set the timing on the middle mark.

 

Check it just for ***** and giggles. A lot of time when people time an engine, they put the slack on the exhaust side and then when the engine turns over it ends up being one or two teeth out of time.

Anyway, what you're describing sounds a lot like an engine one or two teeth off.

 

If I put the timing gun on the crank pulley and it is lined up on the middle mark can the belt be two teeth off?

Does anyone know what the idle rpm should be for this beast? I get different figures everywhere I look. 650 or 750 or 800 with iacv disconnected.

 

I don't know. I've never used a timing gun. All of my maintenance has been done the hard way. Bare hands, a socket set, and a torque wrench.

 

I'm playing this through my head and I cant find a way for that to work out and nothing bad to happen, isn't that how an interference engine comes about? ie: jumping timing. Usually there's like one mark ahead or one mark behind the middle. you can only advance it or retard it one step n it run, i'm no master mechanic but i have used a timing light and had my zc d16a6 sohc down to the block to replace a head gasket when i first bought it.

I have a similar problem and i've narrowed it down to two things.

Firstly my dizzy has a tdc rotor fin type mechanism that tells the tdc sensor when its tdc and one of the fins is chipped off. I speculate that this was done on purpose by the previous owner to make the car run a little more lean.(imo)

Secondly the car does smoke at times when its misfiring and i have the smell of oil which leads me to believe my misfire my be caused by oil passing by my valve seals.

I'm waiting for the summer to get into the valve seals but i have replaced my dizzy with a $75 eBay special internal coil one it fixed my hart start but i still had misfires just at a difference rpm range, which lead me to believe my problem is valve seals.

I have though minimized the problem by using 93+ grade fuel. That may be because of the extra octane adding to me leanness or i may just be making this all up in my head. lol




This is from chiltons honda 1973-1988 this book is a life saver and i got it for like 15$ on ebay. If it helps buy it.

 

just for ***** and giggles, ive had your issue your describing from a swapped sensor on the intake manifold that use the same plug i know the auto and manual intakes are different tho

 

What sensors are you talking about?

 

Thanks for your replys.

Sheela96:

I think that if the timing belt were to be two teeth off, the mark on the block would not be able to line up with the mark on the crank pulley. The marks on the crank pulley would be too far forward or too far back.

LoganHunter:

I have tried another distributor(used) and the issue was still there. It doesn't mean the second one wasn't bad.

I've also tried higher octane gas and no change.

What is odd is that it doesn't alway do this. Sometimes it does when it's cold, sometimes when warm.

 

Start by going back and making sure your wire harness isn't compromised from the swap. A wire may be loose or backing out of a plug. That's a start

 

What I'm saying is that it is possible (and relatively common) if you don't set your tension correctly after changing the timing belt, to be able to have slack on the exhaust side, have all of your timing marks line up perfectly, and then be out of time when it cranks. You obviously know more about this than I do though. Probably why your car is busted and mine is my DD after having the same issues you've got.

 

Oh, SNAP!!!

 

Wow! You really showed me… What are we in the 5th grade here? Isn't that what I asked you and you said you didn't know? Is it possible for the belt to be off two teeth and the timing marks line up? I don't know which is why I ask here. BTW, my car is also a daily driver getting 30+mpg. I take it out of town on a regular basis. 4 to 6 hour trips without ever leaving me stranded.

The timing belt is due for maintenance especially since I don't know the mileage on the new to me motor. I have been putting it off but I'm going to have it done soon especially since it's not too expensive. Hopefully it fixes the issue.

 

Had timing belt changed and valves adjusted. No more stumble or misfire.

Now I have a hunting idle sometimes. I will have to bleed coolant just in case