more knock...

[litdog83z]

When I hit the gas and the turbo starts spooling I get audible knock and then up to 6 degrees of knock retard on the scanmaster, then it tapers off and goes away at WOT.

It's an 87 GN, stock motor
91 octane, 12 psi of boost (until i get this figured out)
Turbotweak chip for 91 octane
Dutt neck stock IC
Stock Turbo
RJC power plate
new plugs/wires
AFPR set at 43psi line off, walbro 340 fuel pump, new fuel filter. fuel pressure around 55psi at full boost..

It's a more recent problem, not sure what could have gone wrong.

TPS is .44 at idle, was only 4.3x at WOT, so I adjusted it, now shows 4.70 at WOT and .44 at idle.
IAC is good,
o2 sensor is a denso, also good.
o2 volts are low 800s at WOT
BLMS check out ok last time I checked..

I'm not sure what else to check.. It smells a little rich at idle still.. It's really starting to get annoying.

 

[suicide six]

All your vitals look good,Any MAF readings?How old are the plugs,wires?Can you feel the car stumble at all?

 

[suicide six]

How old is the gas?Loose crank pulley,maybe bad motor mount,Tranny changed recently? Knock sensor might have been damaged or loose.Grd stud at back of passenger head still tight?

 

[chrisgarrett]

Your fuel pressure may be high. Try 38 off and it should be 42 on. You may be getting rich knock.

 

[scottyb]

I have the same problem, and I posted it today on turbotweak.com. I'll be interested to see replies or your solution.

 

[suicide six]

Try bypassing boost solenoid.

 

[litdog83z]

-plugs and wires have about 1000 miles on them at most
-no MAF readings, i'll get those though
-as for stumbles, not usually, today after I fixed the TPS readings I went wot, got 5 degrees of knock, then it disappeared and I kept pulling then the car stumbled and wouldnt accelerate anymore... at idle I can blip the throttle ever so slightly from 800 rpm or so and get a split second of hesitation
-Gas is brand new, it's done it with a couple different tanks now
-I'll check the crank pulley. I think that the crank sensor interrupter ring might be tapping the sensor. It was bent at one time and I got it straightened at the dealer.
-Motor mounts are good. I also have a engine tie down strap
-No transmission stuff changed recently. Same hardware there, and nothing's changed in drivability
-not sure about the knock sensor.
-i'll check the grounds, they were good last time i checked
-turbotweak instructions say 43 psi line off for my 50lb injectors
-boost solenoid is bypassed already, because when I put in the turbotweak chip it stopped working right and constantly overboosted.

next i'll pull a plug see if it's rich/lean looking and recheck the fuel pressure

thanks for the replies so far

 

[RI-Matt]

Your fuel pressure may be high. Try 38 off and it should be 42 on. You may be getting rich knock.

I think it's the other way around. 42 OFF would give you about 38 ON.


Matt

 

[turbo2nr]

I'm glad someone pointed that out.

 

[chrisgarrett]

I think it's the other way around. 42 OFF would give you about 38 ON.


Matt

You're right of course. Sorry. My fingers type faster than my brain thinks.

 

[Dewey]

That fuel pressure with 50 lb. injectors sounds awfully high. I have green stripe 38 lb. injectors on a motor similar to yours and I'm only running 37 psi of fuel at idle. I was soakin the plugs at 42 lbs. I'm also running 20 lbs. of boost but I have access to 94 octane fuel. I'd pull a plug and visually inspect for a rich condition.

 

[litdog83z]

That fuel pressure with 50 lb. injectors sounds awfully high. I have green stripe 38 lb. injectors on a motor similar to yours and I'm only running 37 psi of fuel at idle. I was soakin the plugs at 42 lbs. I'm also running 20 lbs. of boost but I have access to 94 octane fuel. I'd pull a plug and visually inspect for a rich condition.

What chip are you using though?

EDIT: from the turbotweak site:

- I calibrate the chips at 43psi fuel pressure, but feel free to adjust it for your car if necessary. (Except Siemens 83's, start those at 46psi.) If you have to go further than +/- 5psi from 43, then there may be something else wrong.

I wouldn't think that would be the problem though... It's knock only when I romp the throttle and turbo spools. I can HEAR the knock, it's there in the mid-boost range for a split second and then it goes away if I stay at full throttle and full boost... I'd think if it was a fuel pressure problem I'd get it all the way through the range. The last time I had this problem I found my cam sensor was 180 out. I fixed that and it went away. Now it's back though, not sure if it's related.

 

[litdog83z]

Finally felt the need to work on it again today after going easy on it for a couple months.

I turned the fuel pressure down a lb or so at a time, it seemed to smell like it was running cleaner (before it smelled REALLY rich), but the mid-boost where i get on it good... it's stll knocking... sometimes it registers on the scanmaster, sometimes not... but i can hear it getting worse as the fuel pressure is lowered... just sounds like pebbles in my cylinders...

So i turned it back up to the recommended 43psi line off of the TurboTweak chip, still got the pebbles in the cylinder sound, knock registers, but if i stay in it until it goes away the car seems to die off... It's really starting to get frustrating... i'd really like to turn the boost back up to STOCK levels at least, but I'm not doing it until i figure this out...

Since there's the noise, i'm sure it's knock... same thing happened when my boost control decided not to work and it spooled to 20+ psi... but this happens at mid-boost under heavy throttle...

I just don't know where to go next...

and i keep getting a "Error: Zero Sized Reply" message when I try to search for anything relevant... that's not very helpful either...

 

[litdog83z]

Think it could be because the boost is set below stock? maybe it's getting too rich because the chip is calibrated for 15/16 psi instead of 11/12

dont know how that would cause it, but it's a thought... i dont know much about chips and all...

 

[litdog83z]

Think it could be because the boost is set below stock? maybe it's getting too rich because the chip is calibrated for 15/16 psi instead of 11/12

dont know how that would cause it, but it's a thought... i dont know much about chips and all...

nm that wouldnt make any sense cause it's at low boost...

put in some octane booster and it made no difference

 

[Jerryl]

I am certainly no expert but have had my share of issues.
Let's start from the top.

What is your MAF reading at idle?
Is the TPS in good condition?
Did you verify the TPS to ensure it does not "jump"?
How is your voltage under load?
How are your grounds?
Do you have the PCV connected and is it the correct one?
Crank snesor and cam sensor in good working order?
What plugs and what gap?

 

[litdog83z]

What is your MAF reading at idle? does scanmaster read MAF readings? If so what is it? i have AF of 05 at idle, i'm guessing that's Air/Fuel, L8 of 33, BLM at 124, IAC of 17, NAL (whatever this is) stays at 00,

Is the TPS in good condition? TPS is reading .46V at idle, 4.8 at WOT

Did you verify the TPS to ensure it does not "jump"? Define jump? How can i test this?

How is your voltage under load? voltage stays over 14 volts under load/full boost... never goes below 13.8 any time i've driven it watching it.

How are your grounds? Ground stretch kit bolted to the intake, firewall, head, etc... i'd think it would cause problems at high RPMs also in this case

Do you have the PCV connected and is it the correct one? PVC is connected, with a check valve, both from Kirban's

Crank sensor and cam sensor in good working order? As far as i know, any way to check? They're both set correctly. the only thing I think that could cause a problem with the crank sensor is the wheel got bent, then we restraightened it at the dealer with the right tool, but it seems like it might still be slightly tapping the sensor... i didn't figure that would be a problem...

What plugs and what gap? plugs are AC DELCO R43TS gapped at .035 I believe. I pulled cylinder #1 and it was white... not too bad though, this is after messing with the fuel pressure some up and down.. it smells rich still, but BLMs and the plugs say it's about right.. might just be not having a cat and a little exhaust leak

EDIT: I just checked and my old plugs i have here were R44TS (stock i think)... maybe my plugs are too cold (I was about to order alky injection and up the boost a lot when i got the plugs/wires... then decided to just drive it how it is till i get out of college) My old plugs still look good, i'll put them back in just in case... I think this pinging might have happened before I did the plugs, but I can't remember

 

[suicide six]

Turbo Regal Knock Problem Check List
1. Start-up knock? Normal and usually caused by the starter engaging the flex plate. Usually sets off 1-3 lights.
2. Possible bad ECM or ESC module. Test with good working units.
3. Exhaust rattle – check the down pipe, tail pipes, and have engine tie down strap
4. Boost creep especially top of 1st gear on 1-2 shift.
5. Lean air/fuel mixture.
6. To low octane gas – bad pump gas – try some race gas
7. Too much timing in chip for fuel used. Try different chip.
8. Try cooler spark plugs – use only AC Delco (R43-TS or R42-TS)
9. Gap plugs to .035
10. Check torque converter bolts to make sure they are tight
11. Loose harmonic balancer. Make sure torqued to 200 ft/lb Is keyway secure?
12. Check internal engine noises like timing chains (roller), lifters/rockers, etc.
13. Damaged knock sensor
14. Check fuel pump pressure and volume
15. Proper torque on knock sensor – 14 ft/lb
16. Check Alternator voltage: 13.8 - 14.5v
17. Check computer power wire - they can break internally.
18. Troubleshoot the computer connector power wires and ground wires.
19. Swap coil pack, wires, plugs w/known good units.
20. Swap MAF with known good unit.
21. Check battery ground connection @ block (clean/inspect).
22. Check/change battery cables (both).
23. Are there MAF leaks in the inlet tube?
24. Are there vacuum leaks. Use carb cleaner or WD-40 & spray everything. Does the rpm change?
25. Disconnect the main injector harness - inspect, WD-40. Check for moisture in main connector.
26. Disconnect the coil-pack connector - inspect pins & spray w/WD-40.
27. Is the cat still installed? Is it good?
28. Have you performed a leak down check?
29. Do the rockers open/close? Do we have a wiped cam lobe?
30. Is the boost/vacuum steady @ idle?
31. Is the engine over revving? Should be 4,800-5,200 rpm
32. Carbon in cylinders? Clean with GM engine top cleaner
33. Inter-cooler dirty? Clean inside inter-cooler and fins
34. Oil in intake tract?
35. Check for exhaust leaks, cracked header
36. Battery good?
37. EGR valve in working order?
38. Check that no cables, wires, etc are touching the knock sensor
39. Blown head gasket? Compression test. Should be around 150.
40. Injectors flowing/working correctly?
41. Check vacuum line to fuel pressure regulator for cracks
__________________

 

[suicide six]

what kind of mileage on engine? Check item #12 above if above 80000.Esp timing chain.

 

[litdog83z]

Timing chain has been replaced... engine has 166k miles on it, it's had a head job at one time.. it's not internal noises...

it's an obvious detonation at low boost while the turbo is spooling...