Rough Lean Burn Transition have New Distributor

[Wandering Albatross]

I have a '95 VX with ~190,000 miles on it. The was distributor recently failed and was replaced with an aftermarket one as opposed to a factory Honda to save money. So here is the summary of the issue:

- Replaced entire distributor
- Work was done by local mechanic
- Engine timing was redone by mechanic
- Now the transition to lean burn is about 4 times rougher than it was before the new distributor (at times almost jerky)
- Otherwise the engine is smooth and seems to have reasonable power
- The five wire O2 sensor is less than a year old and other wise the engine does not have any issues
- The CEL is not on

Could the timing be off? What else could cause the lean burn transition to be rough? The issue show us going in and out of lean burn.

Any feedback would be much appreciated!

James

[benfrogg]

The first thing I would do is pull the ECU fuse under the hood for 1 minute or more. (I pull mine for 5 mins usually) If the mechanic did not do this before after replacing the distributor (and there was weak spark before, thus the ECU found some way to compensate for the weak spark like running leaner, etc) the ECU would then have to "re-learn" the new greater spark. This would take many, many miles before it would work well again.
Pull the fuse, let it sit out a few mins, then put it back and and take a test drive.
Remember, easy fixes first!
B

[Wandering Albatross]

benfrogg,

Thanks for the suggestion. I'll give it a try and let you know what I find out.

[N2UAD]

I found that by advancing the timing that the transition to and from lean burn is much smoother.
Mark the position of the distributor and try changing the timing and going for a test drive.
Just my 2 cents.

[benfrogg]

If pulling the ecu fuse doesn't help, I agree with advancing the timing. It's possible it was already advanced before replacement and your mechanic put it back to stock with the new one.
However, I recommend buying/borrowing a timing light, shorting the service connecter under the dash passenger side, getting the engine warm, and setting the timing no more than 4 degrees advanced from the middle number listed under the hood. Your mechanic could also do this for you. Just tell him you want it set as far advanced as he can before the motor starts to ping.
I don't like guessing when it comes to timing.
B

[Wandering Albatross]

You sir are a professional.

I pulled the ECU fuse and let the car sit for ten minutes. I have not been driving much the last couple of days, but went on a half hour drive today and it seemed much improved. The transition to learn burn was much smoother. The timing was unchanged. I am slated to go on a three hour drive on Monday and will have more time to evaluate.

I did not realize that OBDI do much learning of the engine. How long does it take to re-learn if you don't power off the ECU?

Thanks! Will keep you posted on my continued findings.

[benfrogg]

Thanks for the compliments, glad to hear it is better.

Let us know if it stays that way. I don't know how long it would take the ECU to relearn the new variables. Probably a few hundred miles or so.

It might be worth asking the mechanic what he set the timing to. I think it's supposed to be 14 degrees above top dead center, but I run mine 4 degrees advanced from what stock is. I don't get ping there, but some cars do. If the car had the timing advanced before the install and he set it back to factory specs, it could change the feel of the car a lot.

The car may "relearn" and go back to what it was doing before pulling the fuse, so keep an eye out for it. If that is the case, it is very likely to be the timing issue.

Keep us up to date!
B

[Wandering Albatross]

I took the car on a three hour drive on Monday and it is much improved. However, it still seemed to be rougher than I remember during the lean burn transition.

I called the mechanic and he was not willing to advance the timing for me. He shielded himself by claiming that it would void warranties, etc.

I am going to try to dig up a timing light in the meanwhile. I don't own one. I am assuming there is no other way to set the timing besides guessing based on were you are now or using a timing light.

Thanks!

[benfrogg]

Yes, you are right about not having any accurate way to set timing without a timing light. You can often find them in the discount bin at the parts store for <$20 or so.

It doesn't surprise me that the mechanic wont advance timing. How do you still have any kind of warranty? Did you buy it at a dealer?
When replacing a distributor, you don't check timing before the job. You only reset it afterward. He would not have known it was already advanced/retarded before the job took place.
When you do change the timing, mark where it is set first. Then adjust it. See if the problem is fixed. If not, put it back where he put it and search elsewhere. Also, if it is under warranty, you can put it back to the mark before taking it in for service work.

Otherwise, you'd have to figure out what else changed during the distributor swap.
B

[Wandering Albatross]

A quick update regarding the distributor drama. I borrowed a timing gun and from the best I can tell the timing was off by about ten degrees of distributor rotation. I suspect the mechanic might have set it when the vehicle was cold. The car runs MUCH smoother now, but I had questions about the ideal technique for setting the timing.

Here are my timing questions:

1) I realize that the car needs to be warmed up before setting the timing. When setting the timing is the low VX idle (few hundred RPM) okay or should I give it a little throttle when setting the timing? It seems the timing moves a little between idle and a few thousand RPM.

2) I wanted to double check which spark plug wire should be used by the timing gun. I realize it should be cylinder number 1. Is that the longest spark plug wire or the shortest?

3) There are four marks on the harmonic balancer. Three are grouped together and are the width of the plastic timing tab on the timing belt cover. Right now the middle of these three marks is in the middle of the plastic tab. Is this best for fuel economy or does it need to be advanced more? If so, which direction does it need to move (towards the firewall or bumper) and how far relative to the marks? Also, what is the forth that is back an inch or so towards the firewall on the harmonic balancer do?

Any feedback would be much appreciated. I would like to get the timing dialed in as well as possible before giving the timing gun back to my gracious friend. The manual I have is not very informative on timing the engine.

Thanks!