Rattle Sound While Accelerating

[sunny747]

HI,

i'm driving old manual gear mitsubishi. recently i went for gas tuning. I don't know what the guy had asked me in Thai , i just kept on nodding.

now i noticed acceleration decreased a little and i hear rattle sound when i try to accelerate.

any idea what could be the reason?

[Gary A]

The timing needs to be set back. I would guess that it is spark knock.

You should take care of that as soon as possible. It can damage the engine.

Edited August 21, 2009 by Gary A

[Crossy]

Definately sounds like pre-ignition (pinking or pinging depenant upon where you are from).

Timing adjustment required or you will get engine damage

[sunny747]

thanks. it is scary. does anybody know "time adjustment" in Thai? so that i can tell the garage guys. is it a complicated work? my car is old. 1993 lancer.

does it has something to do with the valve?

the sound was not there till i went for gas tune today.

thanks guys.

[Nignoy]

Could also bethe sound of your teeth rattling if the road is bumpy

[Datsun240Z]

Did they changed the distribution belt? If not, can't see what's wrong with the timing?

[BSJ]

The dissy is held firm with one bolt. In a pinch you could adjust it yourself. Move it clockwise one degree at a time till it runs better. If it runs worse go anti-clockwise one degree at a time.

If you got CDI ignition those old things generally run OK if your dissy is out a bit.

[sunny747]

The dissy is held firm with one bolt. In a pinch you could adjust it yourself. Move it clockwise one degree at a time till it runs better. If it runs worse go anti-clockwise one degree at a time.

If you got CDI ignition those old things generally run OK if your dissy is out a bit.

yes you are right. i saw the garage guy messing up with this one. i think they call it valve or wawo something.

what is it and what does it do if you don't mind elaborating. it is attached to the main engine.

i moved it myself little bit and it seems the car is now running smooth.

thanks so much.

[sunny747]

The dissy is held firm with one bolt. In a pinch you could adjust it yourself. Move it clockwise one degree at a time till it runs better. If it runs worse go anti-clockwise one degree at a time.

If you got CDI ignition those old things generally run OK if your dissy is out a bit.

yes you are right. i saw the garage guy messing up with this one. i think they call it valve or wawo something.

what is it and what does it do if you don't mind elaborating. it is attached to the main engine.

i moved it myself little bit and it seems the car is now running smooth.

thanks so much.

Hi Again,

I moved that thing clockwise and it is running well. the rattle sound reduced a lot but i still hear it at 4th and 5th gear. Before adjusting it, i could drive 100 km only but now i can drive at 120 km whereas i could drive at 140km very comfortably till the garage guy moved the dissy.

however, today i was driving at 120km for about 15 minutes and i saw temp was raising. but when i reduced to 100km , then it was ok.

do i have to move it one more degree clockwise? i hear lot of engine roaring but the car doesn't move accordingly.

do i have to change coolant as i didn't change it for 10 months already.

please help.

thanks.

Edited August 28, 2009 by sunny747

[Crossy]

You need to be careful adjusting the timing by 'ear', best to get it set up properly by a different garage.

Running too far retarded will reduce performance and could cause overheating, too much advance and you're into the pre-ignition you were hearing before.

There's also a mechanism inside the distributor (the thing you've been adjusting) that changes the timing with engine speed (auto-advance) which could be stuck, causing lack of top-end oomph.

No need to change your coolant, just ensure there is sufficient. Remove the cap on the radiator (engine cold please), the rad should be full as well as the overflow bottle.

[monty]

Technicians here like to fiddle with the ignition timing a lot.

Basically, when running on LPG you can advance the ignition a fair bit because the very high octane number of LPG (120+).

This will almost completely make up for the power you lose due to the lower caloric value of LPG compared to petrol.

However, running on petrol with this advanced timing will almost certainly ruin your engine!

In short, advancing ignition will increase power, but will increase the chance of pre-detonation (pinging, the rattling your hear).

Retarding ignition will take away the pinging, but will also decrease power. And the sweet point is different for petrol and LPG!

Safety wise it's best to set for petrol, but you'll lose almost 10% power when running on LPG...

[jcon]

Hi Again,

I moved that thing clockwise and it is running well. the rattle sound reduced a lot but i still hear it at 4th and 5th gear. Before adjusting it, i could drive 100 km only but now i can drive at 120 km whereas i could drive at 140km very comfortably till the garage guy moved the dissy.

however, today i was driving at 120km for about 15 minutes and i saw temp was raising. but when i reduced to 100km , then it was ok.

do i have to move it one more degree clockwise? i hear lot of engine roaring but the car doesn't move accordingly.

do i have to change coolant as i didn't change it for 10 months already.

please help.

thanks.

First, congrats on trying to tackle car problems on your own in a foreign language as a woman (IIRC from other posts about you car problems, or maybe I'm not remembering correctly and still hungover - if so, sorry).

Second, what seems to be going on is counter-intuitive in that if you're getting pinging in 4th and 5th gear under engine load, then one assumes that you need to retard timing, but given the overheating symptom you mention at driving at 120kph and also giving the 'engine roaring but the car doesn't move accordingly' it seems that you've already retarding the timing and in fact it needs to be advanced in such a case, no? I could be wrong, it's early - somebody please correct me if I'm wrong.

Ok the overheating could be lack of coolant but that's an easy check (cold engine, of course like Crossy mentioned). But I don't think that's the case.

Is the distributor itself working properly. There are parts in the distributor (like another poster mentioned) and they will mechanically advance timing under increasing engine load.

I wouldn't do this stuff myself if I wasn't confident in my knowledge (even though it's really not rocket science). So I would recommend going to another garage, hopefully with more knowledgeable guys (who also have experience with LPG-fitted cars). The problem could be the timing, or possibly the distributor itself.

Now I have no idea what LPG does to timing issues, I'd assume one needs to retard timing a bit because of the higher octane, but my take on things is that the car was designed to run on petrol so if you're gonna run it on something else, there may be problems.

P.S. Distributor in Thai is "Chan Tchai" and timing is well, "Thai-ming" I think. Yes valves are pronounced "wohw" or even some more awful bastardization of 'valve' by less educated mechanics and in this case valves have nothing to do with the problem (I think) which makes me re-iterate the point to go to another mechanic.

Best of luck.

[sunny747]

thank you so much crossy, monty and jcon. And also other posters who are trying to help me. You guys are very knowledgeable.

"advancing ignition will increase power" does that mean moving the distributor clockwise by some degree? i have definitely lost some acceleration and top speed which was very fine just a week ago till the mechanic guy messed up with the distributor.

so i'm trying to fix it myself with your help. Problem with me is, whenever i take it to mitsu garage, they don't know much about LPG system. I also took it to LPG shop, they fixed but still having the same problem. they do this for free so the amount of time they spend on my car is very less. and the language barrier is there.

so shall i just move the distributor clockwise again and check speed by driving?

Monty, what you mean by "Safety wise it's best to set for petrol, but you'll lose almost 10% power when running on LPG... ".

it's not going to blow up or something right?

[jcon]

thank you so much crossy, monty and jcon. And also other posters who are trying to help me. You guys are very knowledgeable.

"advancing ignition will increase power" does that mean moving the distributor clockwise by some degree? i have definitely lost some acceleration and top speed which was very fine just a week ago till the mechanic guy messed up with the distributor.

so i'm trying to fix it myself with your help. Problem with me is, whenever i take it to mitsu garage, they don't know much about LPG system. I also took it to LPG shop, they fixed but still having the same problem. they do this for free so the amount of time they spend on my car is very less. and the language barrier is there.

so shall i just move the distributor clockwise again and check speed by driving?

Monty, what you mean by "Safety wise it's best to set for petrol, but you'll lose almost 10% power when running on LPG... ".

it's not going to blow up or something right?

I think it depends on the car (someone correct me if I'm wrong) which way will advance/retard the timing. But if you know which direction the distributor rotor turns, then you can advance timing by rotating against it, and retard timing by rotating with it.

I think what Monty meant was that it's better to err on the side of caution (setting for petrol) by not advancing the timing to the full LPG timing if you ever plan on running petrol (because, yes, in that case your engine might throw a rod or something aka blow up) - even if you do lose the 10% power figure mentioned. Monty please correct me if I'm wrong.

The thing about the distributor is that once you set it, either at idle or at load (I don't know how you'd do that unless you had access to a dyno), it should be set for the entire range from idle to full load. The fact that it does not seem to be the case (in your case) makes me think that the distributor is not working properly.

I still say go to a professional, but then again most of the 'mechanics' out there are idiots and the advice you're getting here is probably better lol... but if you can find a good mechanic, then they are worth keeping very close. The Mitsu dealer may not know because they didn't set up the LPG system, so go to the LPG-fitter and have them sit in the car with you from idle to full speed and try to explain it then. Or try out a new distributor and see if that is indeed the case. Or, this would be my personal vote, rip out the LPG system and use petrol.... (there is a reason why Central Department stores have signs saying LPG cars should park on the top floor....)