bad knock after ignition timing!

[Vigo]

A couple points:

'Dead-heading' a pump and getting a high pressure does not necessarily mean it's good enough. That's just the max pressure it can make at 0 flow. All pumps deliver less volume as the pressure rises. The best test for the fuel pump is to put it under the highest pressure AND highest flow situation it's going to see, and check the pressure. Unfortunately if you dont have a pressure gauge with a long hose, you either have to extend the hose or take the hood off to be able to see the pressure while driving high rpm and max boost.

A TBI pump will only make ~50 psi max, in my experience. Not even enough to safely run a stock turbo setup.

But, there's no way the fuel pump is your problem here anyway.

[Shawnethan]

Oh ok that makes sense..

Another clue to this puzzle is that when cold starting, it idle unhealthy for the first 10-15 seconds, not sure if this might be related..

[Shawnethan]

I've taken some time off and have done some research. I know have several thing I would like to try.
1. Change my plugs to copper, copper is more conductive than platinum and platinum generally heats up quicker.
2. My engine was running on 90psi compression for quite some time, and now it has 140, has the comouter relearned itself and wont adjust to the higher compression? Will I have to tune for this compression?
And 3. Retard timing down to 8 or 10, and maybe try higher octane, which will be hard due to the fact I'm already running 91 which is the highest my local gas stations offer. But like I said before, I was running my car at 90psi compression and now its much higher, I believe the knock I hear is some sort of pre-ignition.

Will be retarding timing tomorrow and possibly getting the copper plugs. Will post results shortly after.

[wallace]

It sounds like the knock might actually be mechanical. To isolate/eliminate that as a possibility you can remove one spark plug wire at a time and rev the engine in neutral to see if the knock goes away. If you check all 4 and the knock is still present then it's not a rod bearing or wrist pin. It does sound like one of those two reading your initial description of the noise you are hearing.

[cordes]

Definitely switch out the plugs. I know that the platinum plugs were horrible for problems in turbo motors when they first came out on the market. I would get some stock replacement plugs and go from there.

[Shawnethan]

Slight delay on the plugs but I did retard ignition timing to 10* BTDC. And I know for sure it is not a rod knock because when my cam was 2 teeth advanced there was no knock. Absolutely no knock until I turn the cam back to normal. If anything in the block was creating a knock, it would not be affected by cam timing. It's a spark knock (pre detonation).

[Shawnethan]

Got the OTC 4000E and WOW! I should have bought this a year and a half ago!
Anyways, got up to running temp and went through dataline, here's the results.


Tps min. 0.86
Tps. 0.86
Vac. 19ihg
Veh spd. 000
Map. 09.2igh
02 state. rich - lean
02 volts. 0.12 - 0.80
Rpm. 1k
Knk ret 4. 000deg
Knk volts. 0.00 - 0.02
Knock act. No
Map volts. 0.70 v
Inj pw. 02.0ms
Knk ret 1. 000
Knk ret 2. 000
Knk ret 3. 000
Cool temp. 210f
Elect adv. 000deg
Eng/metric. Eng
Idle rpm. 095
Baro volts. 2.42v
Batt temp. 070f
Batt volts. 13.5 - 13.8
Codes. 14


Anything out of the ordinary? Beside the code haha


After that i Got into Cdr menu and selected "fault codes". Returned back with "MAP voltage too high".


what provides the MAP its voltage?

Edit*** I tested volts and pressure from map and baro during key on engine off, these were my results.

Map v. 2.30v
Baro v. 2.42v
Map press. 27.0ihg
Baro press. 28.4igh

Also when I unplug the map, voltage jumps to a stead 5.02v. Is this a defective map sensor?

[Vigo]

If you can rent a vac/pressure hand pump from a parts store you can test the full range of the map sensor and see what voltage it's returning at your peak boost pressure. With the over-voltage code the most likely scenario is an intermittent short to power in the map sensor.

[Shawnethan]

Ok i will get my hands on a hand vac/pressure pump and post result hopefully later today. And the power short... As in a wiring problem? Exposed wires making contact?

[Shawnethan]

I made quite a bit of progress today!
Got the hand vac pump and volts seemed fairly close to the book in accordance with vac, them I decided to check to ground and it wasnt grounded at al, trace my wires backand found that the ground on the fuel rail had fallen out of the connector that goes to the map sensor, so I grounded that wire and changed to copper plugs and... no more code! made sure everything was hooked back up and went for a drive, didnt hear any knock until I got up to temp and did a few pulls.. barely any knock and only at about 10% throttle. No where near as loud as before but it's still a knock... and during those pulls, got up to boost and started to get up in the rpms, once I got up to 4500rpm the power started to flutter, like I would lift off my seat and then get pushed back and that repeated. My 2 boost gauges (1 stock and an aftermarket ontop the dash) read 11psi, my otc however reads 9psi.. hmm... not really any leads besides vacuum line leaks..

Nevermind. Still knocks just as before

[Aries_Turbo]

what is the OTC saying for knock retard while you are driving and into boost?

Brian

[Shawnethan]

Nothing, knock is never active nor any changes in any of the 4 knock values, all stay at 000

Edit** I am now gettting code 13, now doing some research on it and hopefulky get somewhere

[Vigo]

Are you getting anything on knock voltage? There should be some voltage (noise) even if the computer doesnt interpret it as knock. If you are getting .000v all the time from the knock sensor i would suspect that system is not working right.


Good that you found that ground problem. The MAP works by shunting some voltage to ground and sending the rest back as a signal voltage. With no ground the signal would always be ~5v.

[Shawnethan]

Knock is reading 0.000 to 0.002v, at idle, during the knocking, and during boost i believe. And with my map working properly i have power now, was just hopeful it would get rid of the knock but it did not..

Edit*****
I changed some vac lines and got rid of code 13, and After driving it for about a week i noticed the knock is much quieter when my engine is cold. Still noticable but much more quiet. Still trying to think of something but i'm still stumped. :/

[Shawnethan]

Im still trying to figure this problem out.. its very annoying.. I read somewhere on here that over gapped plugs could cause spark knock. Mine were .035 as the book says, changed then to .025 and no difference.

I also changed my exhaust, previously I have the downpipe, stock cat, glasspack about 3in after the cat, then a 90 and an angled tip right out in front of the rear tire. I cut the tip off and clamped back on the stock axle back pipe and muffler, loss of power in the mid range but so much quieter right now so I can further diagnose this issue, which I can now here the knocking continue to 4 grand under WOT. I'm gonna take my scanner tonight and continuously blip the throttle to mimic the knock and bring out my stethascope again... I've never had an issue last this long :/

[bgbmxer]

Is your cat clogged? Had a car nock and ping due to this?

[Shawnethan]

I have yet to check that.. I replaced it mid last year but the exhaust side turbine seal blew out last month and leaked oil out the exhast like mad.. now that I think of it more that seems more plausable to clog the cat and cause so much back pressure, when the exhaust valve opens, exhaust is trying to escape as well as push back it?does this sound logical?

[Shawnethan]

Ok so I finally found the time to check out my cat, It looks fine, not black on the inside. I cut it out and put a test pipe on, still knocks, so the cat wasnt the issue..