Hey,

I have a Civic with a D15B (Vti) engine, I have only recently brought it but when I got it the owner before me had put a B18C Throttle body on it. It has now been changed back to a D15B TB.

My Issue is that it will sound like it wants to stall after you take your foot off the accelerator, It drops in RPMs straight after.

This weekend I plan to change the Fuel Filter incase that may be causing this but I was wondering if anyone else had any other ideas on what the issue could be?

Any advice would be great Thanks

 

Has it been idling like this ever since the D15 throttle body was reinstalled?

 

It seemed to have issues the day after we got it. Would stall at intersections etc, We thought changing the TB back to what it should be would help but it ended up surging, Mechanic fixed the surging issue though by adjusting the idle but now we just have this issue which is somewhat the same when B18C TB was on but seems to only do it now when you take your foot off the accelerator the revs will drop too low.

 

Check your spark plugs to see if they have oil on them.

 

Have replaced the spark plugs and one had a little oil on it. Also did a compression test.
130, 165, 175, 160. The first cylinder is very low compared to the rest but wasn't sure if that would be causing this problem?

Just a quick note, I sold this car just over 4 years ago (in great condition) and had recently brought it back. I'm sure it has the original fuel filter on and leads, So was going to change the fuel filter because it will be long overdue for replacing if it is the original one.

 

Wow, that could be an issue right there. You might wanna do a leak down to see if its a valve issue. I know I had a b16a2 that would idle rough and cylinder 1 lost compression. I never check to see if it was a valve or piston ring issue because I sold it and dropped another motor in.

 

Is the cylinder with low compression the same cylinder that had the oiled spark plug?

 

Yeah it is the one with a little bit of oil on sparkplug, first cylinder

 

Yeah trying to weigh up the options of putting another engine in or fixing this one if I knew what was causing all this

 

Given that the oiled plug and low compression are on the same cylinder, it probably isn't a valve issue - you're probably either losing compression through the piston rings, or through the valve stem seals.

A leakdown test will confirm.

 

Changed the fuel filter, it hasn't made much of a difference. When we did the compression test we did a wet test on the low cylinder. Was 130 and went to 132 wet.

Will have to take it to a mechanic for a leakdown test at some stage.

It idles okay, It seems to have a slow idle return after revving no matter how high you rev it it will do it.

 

that variation in psi is too much. worry less about the idle and more about your low compression

 

https://www.youtube.com/watch?v=cFB_...ature=youtu.be

Here is a video, First rev is at the rear of the car next at the front. Hard to hear I know because of loud exhaust and loud intake.

Yeah I know the huge difference in compression is a worry, That's why I am wanting to know if that is causing this slow idle return.

At this rate I will just be putting in another engine lol.

Cheers for your advice.