Ideas why engine won't take timing?

[oxford1327]

I'm at a quandry, and am seeking knowledge from the brains trust.

My car won't take timing while trying to tune, all it does is ping its tits off, initial thought was intake or exhaust restrictions but they've since been disproven, as it's got a 3" system front to rear, brand new 100cell cat, and magnaflow 3" inlet 2x2.25 outlet see through muffler, a k+N panel filter etc. 

Nistune ecu, injectors as well are within range and not running out (725cc), plenty of spark with Audi R8 coils and fuel pump delivering ample supply/pressure, intercooler has been changed to a higher flowing water to air unit with much shorter piping, engine has good compression and seems to be feeling healthy and wanting to be fed more, yet something is holding it back and it won't take timing, so am left scratching my head as to what the hell is putting the blockers on..... 

Any ideas at this point would be gratefully received 

 

[Duncan]

Is it a new engine, or are you trying to tune an engine that has been running OK on a standard ECU. If the former there are plenty of things that could be done wrong causing an issue

[oxford1327]

33 minutes ago, Duncan said:

Is it a new engine, or are you trying to tune an engine that has been running OK on a standard ECU. If the former there are plenty of things that could be done wrong causing an issue

It's an engine that's been running fine and smooth, was rebuilt supposedly with forged pistons etc about 10-12000kilometres before I got car, and has kinda always felt doughy in the mid range, even with high flow hypergear it doesn't really come on boost until about 3500rpm

[Kinkstaah]

This is possibly monumentally off topic, but I recently was made aware of a similar issue where a Boosted 1979 BMW 320i was pinging its brains out on like 3deg of timing. After years of living with it we tested the FPR (Which was a well known australian brand) and it was dumping a good liter a minute of fuel into the intake at idle through the vac line.

It's probably not that. But if you've checked everything else.....

(it could also be as mentioned, something done when engine was rebuilt. If your car behaves differently, look for all the things that are done differently to others)

[oxford1327]

5 minutes ago, Kinkstaah said:

This is possibly monumentally off topic, but I recently was made aware of a similar issue where a Boosted 1979 BMW 320i was pinging its brains out on like 3deg of timing. After years of living with it we tested the FPR (Which was a well known australian brand) and it was dumping a good liter a minute of fuel into the intake at idle through the vac line.

It's probably not that. But if you've checked everything else.....

(it could also be as mentioned, something done when engine was rebuilt. If your car behaves differently, look for all the things that are done differently to others)

Car doesn't seem to be excessive on fuel consumption so hesitant to think it's dumping fuel in, though have just installed a new adjustable reg, and 300lph pump compatible with E85, so we can test that theory once car is done with installation of flex fuel stuff. 

Have had 2 jdm enthusiast /specialized mechanics looking at it and it's got them scratching their heads as to why its like it is, they've both worked on it separately as well as together and short of removing and peeling engine open we've started to make incremental changes to parts, then test and if no change try something else, change, test and so on

 

[Kinkstaah]

The BMW mentioned also wasn't bad on fuel, but it did have a mysterious issue of always fouling two spark plugs, due to the location of the runners this made a whole lot of sense when we looked at the FPR. It could simply be something like the wrong pistons used, sky high compression ratio etc too.

E85 will help with the pinging, but obviously better to find the source ?

[oxford1327]

1 minute ago, Kinkstaah said:

The BMW mentioned also wasn't bad on fuel, but it did have a mysterious issue of always fouling two spark plugs, due to the location of the runners this made a whole lot of sense when we looked at the FPR. It could simply be something like the wrong pistons used, sky high compression ratio etc too.

E85 will help with the pinging, but obviously better to find the source ?

What would be the differences if any between rb25det pistons and rb25det Neo pistons? Anybody aware of what issues they could cause with clearances etc

[Kinkstaah]

Pretty huge. If you had Non-neo forged Pistons in a Neo motor, I.e R33 RB25DET pistons in a R34 RB25DET Neo which the S2 Stagea has, your compression would be massively high.

High enough that whoever assembled the motor would surely notice...... surely....

It might be the other way around, I can't quite remember. But you'd definitely have compression ratio issues if the wrong pistons end up in the wrong block/head combination. (neo vs non neo)

[oxford1327]

1 minute ago, Kinkstaah said:

Pretty huge. If you had Non-neo forged Pistons in a Neo motor, I.e R33 RB25DET pistons in a R34 RB25DET Neo which the S2 Stagea has, your compression would be massively high.

High enough that whoever assembled the motor would surely notice...... surely....

It might be the other way around, I can't quite remember. But you'd definitely have compression ratio issues if the wrong pistons end up in the wrong block/head combination. (neo vs non neo)

I have the build sheet for engine, and sadly all It says is forged rb25det piston kit, but no part number to identify if it's neo or otherwise, so will do a compression test and check figures I spose, apparently std comp is about 170-175psi range, I'll also attempt to call the engine builder and see if they can remember what they were, though it was around 3 years ago so don't hold much hope

[Ben C34]

Kinkstaah is correct, non neo pistons in a neo engine will be very high comp. The neo combustion chambers are a fair bit smaller than R32 and R33, I think like 10cc or so.

[AngryRB]

I would have the injectors checked for flow just to rule that out.

And might not be but the vct gear could be playing up, that can do odd things, might be too advanced (the slots at the back).

Edited June 18, 2019 by AngryRB

[oxford1327]

Have spoken to engine builder, and they can only vaguely remember what piston they used in engine, said they reckon it was a modified wiseco piston, so my thought is that next steps are comp test to see if excessive, and the throw E85 at it and see what it does from there. 

Then if that fails yank it out, peel it open and put a proper f**king set of neo piston in it just to be certain 

[oxford1327]

Just now, AngryRB said:

I would have the injectors checked for flow just to rule that out.

Brand new bosch 725cc from efi solutions and no sign of running out of room for flow, and have just got new pump and adjustable reg fitted ready for E85 

[Duncan]

So, it sounds like it's been running, but wrong, all along. Poor midrange suggests it couldn't take timing back when they first tuned it either.

Start with the easy stuff like ensuring the timing is all OK. Check timing with a light obviously, but also check TDC is correct on the balancer (skidfactory did a good video on checking this), then check the cam gears are correct and not adjustable, and then check the timing belt is not a tooth or 2 out.  All that you can do without pulling the engine apart.

[oxford1327]

48 minutes ago, AngryRB said:

I would have the injectors checked for flow just to rule that out.

And might not be but the vct gear could be playing up, that can do odd things, might be too advanced (the slots at the back).

I'll see if the vct bits have been sussed out, new timing belt and adjusters fitted in last couple of weeks to ensure it hadn't been skipped a tooth on pulleys etc, did ask if the bull nose bit on front of cam was free and clean and all reports were it looked fine by them. 

When you say slots in back, do you mean on the bull nose bit or the cam itself? 

[AngryRB]

Why not fill with E85 and see how it reacts.. do a few pulls, it might pull hard 

[oxford1327]

Just now, Duncan said:

So, it sounds like it's been running, but wrong, all along. Poor midrange suggests it couldn't take timing back when they first tuned it either.

Start with the easy stuff like ensuring the timing is all OK. Check timing with a light obviously, but also check TDC is correct on the balancer (skidfactory did a good video on checking this), then check the cam gears are correct and not adjustable, and then check the timing belt is not a tooth or 2 out.  All that you can do without pulling the engine apart.

New balancer is being fitted already as old one was getting tired and perished, will then try timing light etc, cam gears are std OEM stuff, and new belt was fitted couple weeks ago whilst it was opened up to check it hadn't skipped a tooth or 9.

Currently waiting for the ecu to return from Nistune after having E85 harness fitted and a general checkover found nothing out of the ordinary 

[AngryRB]

9 minutes ago, oxford1327 said:

I'll see if the vct bits have been sussed out, new timing belt and adjusters fitted in last couple of weeks to ensure it hadn't been skipped a tooth on pulleys etc, did ask if the bull nose bit on front of cam was free and clean and all reports were it looked fine by them. 

When you say slots in back, do you mean on the bull nose bit or the cam itself? 

On mine though they are fairly advanced and i dont have pinging issues on E85, i do have high comp though. Just somthing to consider.

Edited June 19, 2019 by AngryRB

[admS15]

What was the previous intercooler setup and are you sure the new one is more efficient? Do have iat readings?

 

Is the intake tract and cooler piping internally clean or is there oily residue from blowby, excessive blowby can also cause pinging if substantial enough. Catch can can help here.

 

As already stated e85 will help mask the issue but better to be sorted properly.

[Duncan]

well, assuming you trust the guys that did the timing, I think your engine has a mechanical issue like wrong pistons, or decked block and head. So either you make the best of what it does take, or pull it down and check....