Pinging at low revs

[Roundy]

Hi Guys,

Back from a rather unsuccessful dyno session, working up the rev range slowly, and get to 2500rpm at full load now with approx 2psi boost, 9:1 compression ratio, 13:1 fuel ratio, and 20° timing the engine was pinging like a bitch.

To get it to stop the timing had to be backed off to almost 0°

Any thoughts on potential causes?

Cheers
Nathan

[trd_st184]

I know this might sound silly but has the fuel filter been replaced recently? Might be blocked up. That or a blocked up cat converter

[Roundy]

Forgot to add, fuel ratios were 13:1

Fuel filter is brand new when i replaced the engine.

Cat could be one option, I was going to remove it anyway.

[trd_st184]

Just on the possibility that the timing on the actual belt could be out? I remember that when my 5sfe was out one tooth out and it would be down on power considerably. The person that did the timing belt prior actually turned down the timing on the distributor as much as possible, even then the timing still read something like 5 degrees (that was with the distributor turned as much as possible).
I checked the belt and adjusted it one tooth in the correct direction and the car ran fine after that.

Just a few thoughts. I love your car mate, looks awesome

[jondee86]

To get it to stop the timing had to be backed off to almost 0°

How are you reading timing ? Timing light or laptop ?
How are you adjusting timing ? Dissy or programmable ECU ?

If you have a programmable ECU, you need to ensure that the ECU is synched to the actual physical engine timing, so that what the ECU shows is the same as what you see with a light.

Cheers... jondee86

[fixeruperer]

id look at cam timing too, and use a timing light to check timing.

how old is the fuel ?

[Roundy]

Fuel is a month old.

Timing was through the ECU, however I had checked the timing with a timing light before getting it tuned, and adjusted it so that it was correct.

[jondee86]

Yeah... have to eliminated all the possibilities, so check that TDC down the plug hole on #1 actually matches zero deg on the timing cover. Then while you have it at TDC, pull the timing belt cover and check the cam timing.

Cheers... jondee86

[JustenGT8]

5sf crank pulley marks might not correspond well to a 3sgte head?

EDIT on second thought that doesn't make much sense but something physical must be out of wack.

[lexsmaz]

What motor is it ? & is it a fresh rebuild ? & have you dyno'd it before as a base line comparison ..

I wouldn't think its a blocked cat as it would increase back pressure & so less scavenging & so combustion would be contaminated with old burnt fuel & it would drop combustion temps much like a EGR does ..

[Roundy]

3SGTE, yeah fresh rebuild and first time it has run.

[lexsmaz]

What was done to the motor & was the head or block shaved / decked & who worked out the compression ratio & was there any head work done to the actual bowl chamber ..

[Roundy]

5S crank, head/block, not much if any shaving (can't really recall)

Compression ratio, the pistons were 9:1 for the 5S Crank.

I cc'd the head, before any work admittedly, and double checked the compression ratio based on that and the piston specs.

The head cc's were 49, 1mm head gasket, and 13cc dish in the pistons, for 2.14l compression

One of my checks will be to cc the engine as it sits at the moment.

Quick sanity check, if 1mm was shaved from the head, worst case scenario would be 9.7:1 comp (based on 86.5mm bore)

[JustenGT8]

It's nothing to do with the comp ratio, something is fundamentally wrong with the timing, be in physical, electrickery or both.

[trdee]

as above. like i mentioned in your thread, for it to be pinging with almost no load on it then it cant be the CR, it has to be timing imo..