85 m110 popping
 

My car just started backfiring the other day, but it only does it if I'm going down a hill with back pressure on the motor and as soon as I touch the throttle it makes one POP. I'm assuming it is a fuel issue. If any body can help with diagnosing my issue I would appreciate it.

It's through the exhaust not the intake.

One more thing I would like to add is injectors are new, and injection k-tronic was rebuilt. I only have about 1500-2000 miles on those parts. And when I start it when it's cold it idles up for a second then almost stalls for second then idles back up. Not sure if that has anything to do with it but I thought I should add that.

That version of K-Jetronic incorporates a closed-throttle coasting fuel shutoff; when the throttle is reopened the resumption of fuel flow can cause the pop.


The two are linked; likely the overall mixture is a bit lean. The start sequence may have cold-start injector fuel present, then that is exhausted, then the Warm Up Regulator (WUR) picks up the mixture.
The pop can be caused by a lean condition when the fuel flow resumes; the air flow increases faster than the fuel flow, leading to a brief leanness.

[As to your other post: Expect engine water temp to vary between 80-100C., depending on ambient conditions, and power demand (climbing a grade vs. descending).]

Thanks for the info. I'm assuming I should probably get the mixture adjusted then(weird though how it just did the popping out of the blue). I know where the adjustment for the mixture is, I'm wondering if it's hard to do, to get it right. And about the temp mine seems to stay between 85-100, so I guess I'm ok there.

I also wanted to ask if you think that the popping issue could damage the engine

One more thing that's been kinda bugging me is what is the best fuel to run(unleaded regular, midgrade, or ethanal free super)? Right now I have the ethanal free, I figured it would be better but I was on regular.

I have another issue when I start it when it's cold it revs up then almost stalls for a second then idles back up. But yesterday I noticed that if I turn the key all the way to engage the fuel pump and do this twice and starting it on the second prime of the pump it starts normal. I was thinking maybe the problem is the pressure regulator on the intake manifold. Or could the accumalator cause this? Frankly I don't even know what the accumalator does.