Engine Pinging

[Pajo1]

Hi All,

just wondering if anyone has had issues with engine pinging? My NM 3.5 ltr has suddenly started pinging and cant find the fault. Changed the fuel filter, pump, pressure reg and no fix so I took it to my guru who plugged in the MUTTII diagnostic to see what he could find. The diag tool told us that everything is A OK and nothing to report. All variables are perfect, timing is spot on and so is the O2 sensor. There was nothing out of whack. The pinging just started suddenly. There was no gradual increase in the noise, it just started. Noticed that this happens only once the engine is warm to hot op temperature. Now my car is also on gas and obviously the engine runs perfectly and smooth as silk on gas but when i switch over to petrol, ping ping ping something fierce.

The only thing he did find was that the TPS (throttle position sensor) was out a little bit but had that adjusted and made no difference. Checked any fault codes and none to be seen.

So now I ask you all, any ideas? its driving me nuts. MM has said that the ECU is knackered but had that checked and thats fine, even put in a brand new one (borrowed) and made no difference. MM checked everything we did and they cant find it either....

can anyone help?

I believe that this is caused by reduced fuel flow but thats also been checked and is good. Car has been on gas now for 4 years and its the first time this has happened (last 3 months)

[swanie1975]

pinging?

does it happen on gas only, both, or petrol only? what octane petrol are you running? have you tried an octane booster just to see if it stops?

it seems youve tried most things - maybe time to start back at the basics


cheers ryan

[Pajo1]

no it only happens on petrol. runs sweet as on gas. using standard unleaded and have done the whole time. Thinking i might try 98 octane and no I havent tried an octane booster. Just spoke to my dad though and he said that he has only ever heard of it being caused by dirty fuel which can cause blocked injectors...hmmmmm

[swanie1975]

pinging

just a thought - has it ever backfired on the gas? is it injected or the regulator system?

i was having trouble with mine on petrol after the previous owners had it backfire and it was running ok on gas but idled erratically on petrol. also a slight ticking noise on acceleration. The previous owners had the petrol injectors cleaned and then i bought it and did plugs and leads. still the erratic idle on petrol and a very slight hesitation on lpg (could feel it more than notice driving).
ive just swapped out my airflow meter with the neighbours and it fixed the problems straight away, idled smoother on gas and great on petrol. also accelerated better on both. ive bought a 2nd hand airbox and AFM from the wreckers as MM want $900 for a new one that!!!!

anyone local you could swap out bits with to narrow it down?

cheers ryan

[Pajo1]

Hi Swanie

yes mate she's the standard gas system and yes it did backfire dramatically 2 years ago however apart from destroying the airbox, the AFM was intact and functioning. I did have it tested this morning and it showed normal function but im getting it swapped to check it against the new one. However........update is that i just drained the tank half hour ago and stuck a bottle of liquimolly injector cleaner, followed by a tank of premium unleaded and hey presto, no more pinging.....as yet.......(fingers crossed)... I dont understand why as i have had the car for over 6 years and only ever had standard unleaded in it and she ran fine so far so good. just about to go for a drive to see how she goes so will check back later and let you know how it goes...

cheers
Steve

[donald]

does it burn oil ,might be the heads and the topend has a lot of cabon in it ,this happend to my 3.5 ,used to ping down low under load,took the heads off to do the valve stem seals ,the top end and top of the pistons had heaps of cabon build up on them due to burning oil ,once i cleaned the heads up and the carbon on top of the pistons ,no more pinging

[Pajo1]

No she doesnt burn oil. Definitely dodgy fuel but the tank clean sorted that out however a new problem has emerged. Today I went to pick kids up from school and being a warm day here in adelaide, i decided in petrol mode with aircon on. engine was quiet however i noticed when the aircon is on, she has a flat spot upon initial take off and then very sluggish once going. When i turned the aircon off, she roared to life so obviously i switched the aircon back on and she went back to being a sleepy giant again...any thoughts?

[Pajo1]

Update......

found the flatspot issue. When we changed the fuel filter, there is a small cap that clips on at the bottom and that keeps the pump in place........mine was missing. Seems my mate who did the filter change forgot to refit it and only realised after he had done the job and put it in my console but didnt tell me. I found the cap not realising what it was and ditched. When i removed the filter to see what was going on, I found the pump had fallen out from the filter therefor not enough to no fuel was going to the injectors. I noticed the colour of the pump and filter housing and noticed that it was the same colour as the cap i had chucked. Sooooo i went bin scavenging and found it luckily. Clipped it back on after refitting the pump and sweet. Put the car back together and went for a spin.

happy to report that my baby is purring beautifully and driving like a dream!