Detonation issues, I think.?

[turbo39151]

I am experiencing a "dieseling" sound when I get aggressive on the gas. My boost is funky - it shoots up to 20-23 lbs and I do not have an adjustable wastegate... (I haven't touched it.)

It sounds like it's coming from that tranny but it's not (and the tranny is fresh).

Particulars:
86 GN
New Walbro 340/hotwire
NEW fuel filter
MSD 50LB
TT chip
43 lbs w/ vacuum off
stock turbo
dutt neck IC
62mm tb/matched plenum/rjc power plate
KB intake
LS1 Maf/ trans+ (not adjusted only set to base levels)
91 OCT (california gas )

I was going to add alky to "cure" the condition but I suppose that the condition should not be present at all. Also, noticed slight wobble on the turbo blades. They touch the housing so I'm shopping for a new turbo.

This wouldn't cause the dieseling noise would it???
Besides changing the turbo along with adding an adjustable WG, I should be fine, No? I don't know what else to do to fix the problem.

Any ideas?

I don't have a scanmaster yet... (soon very soon)

 

[turbot2496]

Your running way to much boost. Your probably getting alot of detonation. If you don't have an adjustable wastegate then check the all vac hoses coming from the turbo for leaks.

 

[turbo39151]

Will do. So far haven't found anything out of the ordinary. I'll have to check again...

 

[Quick6'n'-K.C.]

WOW

Way too much boost for your car...
Take a piece of hose and loop from the compressor side of the turbo straight to the wastegate. Your boost will be lowered to about 14-15.
Leave the boost down low till you get a scantool to let you know how much knock your getting.

Your very lucky you didnt blow a headgasket from too much boost and not enough octane!!!!!!!!!!!!!!

BW

 

[turbo39151]

I was going to do the bypasss as suggested when I noticed that one of the hoses was really dry-rotted. So, I just slapped on a piece that I had lying around. I took her out for a spin and hit 15lbs with a little hint of "dieseling' at the upper end.

Is there anything else I can do to stop that last bit of noise... ( I assume it's knock. I'm running California 91 Octane...

Any other suggestions?

 

[Quick6'n'-K.C.]

Yes, replace the fuel filter and do a search here on how to hotwire the fuel pump. Just some 12 guage wire and a relay or purchase a "kit" from a vendor.

The factory wiring to your fuel pump is old and doesnt provide enough voltage to the pump anymore, more voltage to the pump will help.

If you loop the compressor to the wastegate, then it actually might lower the boost down to 12psi, this will get rid of the knock you are hearing....

Any knock is bad, if you can actually hear it, ITS REALLY BAD!!

Do you have a aftermarket boost gauge or are you reading the values on the stock gauge cluster?
I would lower the boost for now, you will save yourself some headaches in the future with a blown headgasket.

Once you purchase a scantool such as a scanmaster 2.1 then see if the car is still knocking, it displays the timing that is being retarded due to knock from the motor.
It displays your coolant temp,02 values, trouble codes,mph,rpm,ect ect ect... very nice tool for the 225.00
BW

 

[turbo39151]

Actually, I'm running a new Walbro 340 w/ hotwire, a new fuel filter, new MSD 50lbers, TT chip, KB Ram Air w/Trans+ and LS1 MAF, 62mm TB/ported plenum RJC Power plate, Dutt neck I/C etc... Also using aftermarket VDO Boost Gauge.

As you can see, I've covered just about everything that I can cover... Any other ideas? I was going to do the bypass loop but I'm worried as to why I'd have to do it in the first place... It should be ok with what I've got. (I have never touched the boost other wise)

On a side note, I've discovered that my stock turbo has some side to side play and will touch the housing. Could this be causing the problem???

 

[D's GN]

The noise you are hearing is detonation, you are lucky you haven't blown a headgasket. A scan tool is a must before you decide to nail the pedal, this way if you see a bit of knock retard you can let up instantly. When you actually get to the point of hearing detonation like you have, your bearings and headgaskets are taking a sh*t kicking. I would look for a stuck wastegate puck due to rust in the swing arm, make sure the swing arm moves freely and doesn't bind. You might only get 12-13lbs boost before detonating depending on your tune. Alchohol is definately a good idea, especially with crappy 91 octane. HTH

 

[turbo39151]

Does anyone have a pic of where I should be looking for the rust on the OE (non -adjustable) wastegate? I know where it is but I'd like a specific spot to focus on as I've looked at it before but it seems ok and I didn't see rust.

I just want to be certain...

 

[Quick6'n'-K.C.]

Well, if the puck was rusty inside the bushing you wouldnt be able to see it.

What he should have said was to take the wastegate rod off the swing arm and move the arm to see if it is sticking. I dont think it is rusted because if it was stuck shut, you would get around....ooooohhh 30 psi or so.
If it was stuck open, you would get.....ooooohhh 8 psi or so...

15 psi is typical for the chip your running, but detonation means something isnt right, either too much timing in the chip your running.... or you might have a leak to the fuel pressure reg...or your running more boost than your gauge show, or it could be rich knock...

Got a scan tool????? Guess you dont have that covered huh? :biggrin:

I just ran into a problem with my car last week, my check valves were both blown... 1 is next to the egr on the drivers side valve cover, the other is the really long vacuum hose to the charcoal cannister.
I did get a few times where the knock was over 12°, thats bad!!!
Replaced the check valves and no more knock
You should not be able to blow thru the check valve, and they only go one way!!! VAC toward the throttle body upper distribution block, its the vacuum source at idle, and the pressure source under boost.

BW

 

[turbo39151]

The chip I'm running was burned by Eric from TurboTweak for the specs on my car that I sent him. Just a street chip, nothing fancy...

Neither the FPR or the Injectors are leaking. I'm running 43lbs with vacuum off. (as per the directions on the chip.). Lou C. checked and adjusted the TPS and everything seems to be in proper working order...

I went out and pulled on the Arm for the WG and it moves freely with some effort but no sticking at all. Also, I checked both check valves, pulled them both off and blew through the black portion (not the white) and neither would allow me to blow through. So, I'll assume that they are both in proper working order.

I suppose I should go through and start swapping all of my vacuum hoses. The ones I have changed did not leak but were dry rotted. So, I assume that the other hoses are probably in the same condition.

Are there any other things that I should be looking at?

I'll be picking up a scanmaster in the next week or so if all works out...

BTW, thanks for all the help. The pic was helpful too. I'd don't know if I'd ever get this car running right without the good people in the TR community...

Thanks again.
-Louis

 

[Quick6'n'-K.C.]

I suppose I should go through and start swapping all of my vacuum hoses. The ones I have changed did not leak but were dry rotted. So, I assume that the other hoses are probably in the same condition.

Are there any other things that I should be looking at?
Thanks again.
-Louis

I would replace the other hoses on your turbo along with all the other hoses on the engine, including the ones on top of the throttle body distribution block.

If you havent changed the plugs lately, pull some out and see if they are black (rich) or white (lean) till you can purchase a scanmaster.
I run NGK UR5 gapped at .032 or AC delco 42s
What have you been running?

No problem with the help :biggrin:
BW

 

[turbo39151]

I'm running fresh AC 42's with new wires. All of the 1.5" lines on the distro block are new as I added a new billet block so I'd be able to swap to vacuum brakes.

I bought some new hose today for all of the other ones that are in need of swapping...

The car feels like it's running perfect. Not too lean, not too rich. I've been wondering if she needs a little more fuel pressure due to the big injectors and ram air, tb, etc.

I have the car on stands as I'm swapping the shocks at this time so I'll have to post up again when I take her out which will probably friday night...

 

[turbot2496]

Also splash some kind of octane booster in there or some race gas.... You could be doing all this fretting over a bad tank of gas...

 

[Ormand]

Also splash some kind of octane booster in there or some race gas

Octane booster is pretty useless. But a couple gallons xylene or toluene would let you know if octane is the problem.

 

[turbo39151]

I changed every vacuum hose I could find. Still have the issue. I was gonna add some alky but I wanted to make sure that I wasn't just putting a band aid on a bigger issue. The gas isn't from a bad batch. It happens every tank full. I run two other turbo cars (one of them has the boost turned up a little more than stock) and neither exhibit this problem.

I thought I had gotten over the "too much boost issue" but I still hit almost 20 psi. (I even have a new boost gauge on order to cover the "bad gauge" theory.) If I swap the turbo and wastegate for a new one will I eliminate the problem? Or is there something more that I need to address. It was also suggested to me that the puck insde the DP could be not making a good contact I have no idea.

Any other ideas??

 

[Quick6'n'-K.C.]

WOW

Way too much boost for your car...
Take a piece of hose and loop from the compressor side of the turbo straight to the wastegate. Your boost will be lowered to about 14-15.
Leave the boost down low till you get a scantool to let you know how much knock your getting.

Your very lucky you didnt blow a headgasket from too much boost and not enough octane!!!!!!!!!!!!!!

BW

Do that and then...

If you still have high boost, the wastegate diapragm could be torn...

 

[Hacksaw]

Check out the wastegate solenoid. When it fails it can cause overboost or under boost.

Union 76 has 100 octane R+M/2 street legal Racing unleaded around here in San Jose. I also know it's in other parts of the state. Trick Gas out of San Diego also has their version of racing unleaded around.

 

[turbo39151]

I'm back.

I bypassed the wastegate solenoid and it seems to have alleviated the spiking problem. But now since I've added alky and a few other items I have a stumbling issue:

I added all new gauges (knock, volt, oil pressure, water temp and boost/vacuum) I also added the old style SMC kit.

Car runs fine. But now for some reason the "Brake" idiot light is on. wtf?!!?
Pedal is really hard. I have the vacuum conversion.

Also, while I was trying to dial in the alky, I boosted, tore the tires loose in second gear :biggrin: and then the engine bogged .

I'm running 43-45 lbs fuel w/ vacuum off.

I also have a trans+ and ls1 MAF but everything is at baseline. I have yet to purchase the scanmaster (i know, i know, shameon me )


When I press the test button on the alky module the engine should stumble. Mine almost dies! What am I doing wrong?

Anyone??

 

[turbo39151]

I tried to tune the alky today and re-connected the bad wastegate solenoid and I can hit about 20 lbs with no knock now. But my freshly rebuilt tranny doesn't want to shift into the next gear

What now?