Annoying Vibration at Low Engine revs and Stationary.

[JAS21]

I don't think it is an engine problem

Mazda Lantis, my wife’s from new. Top end overhaul about a year ago, even then I noticed a vibration at engine idle speed.

I hardly ever drive this car, in fact we only recently got it back from my wifes daughter. The plugs were only changed few weeks ago just to see if that improved things, it didn’t. Anyway, today I used it and thought that the vibration was even worse.

When stationary and at engine idle speed (about 700rpm) I noticed that vibration was worst when in ‘D’, than it was in ‘N’. Out of interest I put it into ‘R’ and the vibration just about ceased, it vibrated again when put into 'P'. Increasing the engine speed to 1200+rpm, ‘N’ selected and the vibration also pretty well disappears.

Back home and lifting the bonnet (hood to some of you) the top of the engine appeared quite steady at engine idle speed and in 'P'. But the steering wheel vibration is still there.

So what is it? bottom engine mounting or Autobox or …………? I’ll get my wife to take it to a Mazda Shop for an opinion but wondered what some of you experienced guys think is the problem.

Basically it is only in 'R' that there is very little vibration.

[Jitar]

I'd be suspicious of Engine or Trans mounts

[JoeW]

Also a bad fuel system might cause the engine to misbehave (erratic RPM or sudden drops). We had a car here at our repair-shop with a similar problem.

We replaced the fuel pump and that solved the problem. His engine mounts were still ok.

[JAS21]

JoeW, on 06 Nov 2015 - 20:38, said:JoeW, on 06 Nov 2015 - 20:38, said:

Also a bad fuel system might cause the engine to misbehave (erratic RPM or sudden drops). We had a car here at our repair-shop with a similar problem.

We replaced the fuel pump and that solved the problem. His engine mounts were still ok.

Thanks .. I should have added that the engine speed is steady, it does drop slightly when 'D' or 'R' is selected but remains at a constant speed ... I think/hope that it's a engine/transmission mount problem as Mr Jitar suggests.

Edited November 6, 2015 by JAS21

[Pomthai]

Might be as simple as throttle cable stretched over the years. A little adjustment taking up the slack and increase the idle to 750 or 800 whichever sound smoother.

I think 700 is a little low.

Next look at engine mounts.

[hugocnx]

Might be as simple as throttle cable stretched over the years. A little adjustment taking up the slack and increase the idle to 750 or 800 whichever sound smoother.

I think 700 is a little low.

Next look at engine mounts.

+1

Or even more RPM at idle.

Edited November 6, 2015 by hugocnx

[WarpSpeed]

All the above good starting points.. The idle does sound a little low with A/C running, maybe the A/C idle sensor is failing? Or vacuum leak which is very likely on an older car, check for cracked and stiff lines and joints, even sometimes just begin stiff around the joint can cause poor sealing while running and air intrusion into the intake system, also check the intake tube very carefully for cracks.

[Alration]

I'm surprised that no-one has suggested that it may have been a "flood" car, have you explored that angle? There's a lot of them about. Apparently.

[JAS21]

I'm surprised that no-one has suggested that it may have been a "flood" car, have you explored that angle? There's a lot of them about. Apparently.

Not really ... as said my wife bought it new nearly 20 years ago.

[JAS21]

Sounds like an engine/box mount but I would have a good look for something touching the chassis or bodywork (exhaust) that might have happened during assembly. .

Yes, it needs to go up in the air and see what happens underneath when D N R and P are selected.

[JAS21]

transam, on 07 Nov 2015 - 12:47, said:

Sounds like an engine/box mount but I would have a good look for something touching the chassis or bodywork (exhaust) that might have happened during assembly. .

It is mounts ... the guy who does just about all the maintenance on this car ... he even installed the LPG years ago ... confirmed it just now. He's getting me a price for genuine Mazda bits and also copy parts. He says he fitted copy parts 2-3 years ago so maybe I'll have to dig deep and get Mazda ones ... I suspect a lot of thb. It still looks good so a deep dig it will be I guess . Mrs Jas has love it from new and wants to keep it ... step-daughter has tried to destroy it many times thought .

[Jessi]

Same problem with my 96 Corolla. I had the engine mounts replaced ( 3 years ago) with non genuine ones but the vibration is still there, I just put up with it and when at a stop I put it in N, the vibration stops. The price of genuine engine mount were off the scale, like get a personal loan from the bank.

Edited November 8, 2015 by Jessi