Knock Retard

[Pliskin1]

Sorry guys - I know there's plenty of threads on this subject, and did some reading, but still not sure what to do.

As I mention in any thread I start - I am not very mechanically inclined, so bear with me.

Made some changes to the car recently, and now I'm having knock issues according to my scanmaster, although I didn't hear anything. My mods are in my sig. And I run 93 octane. That's all.

Converted to vacuum brakes. All is good with that. Don't see how that could tie into my retard anyway.

Only other two changes I made were an adjustable wastegate and new fuel pressure regulatory. I did have a few rusty fuel lines changed as well.

All this work was done with the help of my daily mechanic.

We set the FPR at 43# off vac. Connected, it was right at 38/39. Adjusted wastegate, took her for a spin, and no problems. At WOT, I'm right at 16# of boost. Made several runs, and no codes or messages or knock retard. My mechanic kept an eye on the scanmaster while I looked at the boost gauge (I did not want to overboost). This was 2 days ago.

Today I'm out taking a run. Roll into WOT from about 40mph, it downshifts, accelerates, and I see the retard # pop up so I back off. Pull over and check the recall: 10.1 degrees at 52mph. 789 millivolts. I ain't no mechanic, but I know that 10.1 is NOT good.

Prior to these changes, there was never any retard on it. None. Zero. And if it matters, I was only pushing 11# of boost (which is why I changed the wastegate).

I also had a fuel pressure gauge installed in the engine compartment. When I looked at that today - and I'll admit its not a top of the line gauge - it appears to only be reading about 29-30# at idle with vac on and engine warm. The other day, it was definitely reading right around 38/39 with the engine warm.

All my other scanmaster readings seem to be within spec.

Thoughts? Is it something with my new FPR? I only changed it because I figured "why not", the original one was still on there. Or, has having a new FPR with correct delivery now uncovered a new problem that wasn't visible under the previous one?

Appreciate your help.

 

[Pronto]

How old is the fuel pump? Hot wire?

Posted from the TurboBuick.Com mobile app

 

[Pliskin1]

Fuel pump & feeder kit were replaced in March of this year. Have about 800 miles on it since then.

 

[dynoman]

Get a gauge with a hose on it long enough to view it through the windshield , tape it down under the wipers & take a ride, roll into boost . Make sure fuel pressure rises 1 for 1 with boost. Was the knock at the shift point ?

 

[Pliskin1]

Thanks Dyno. Will see if I can get my hands on the hose and gauge - not something I own.

The knock (and again, I didn't hear anything) came right around the point that it shifted. I don't know my exact speed when it downshifted - roughly 40 -, and I'm wondering if maybe I jabbed into the throttle rather than rolled into it. But the reading definitely came after the downshift.

I glanced at my turbo gauge too make sure it wasn't too high, and then went right the scanmaster. That's when I saw the 10 (thought my eyes deceive me) so immediately released throttle. I'm not familiar enough with these cars to know if it was going to blow up.

 

[dynoman]

I asked about the shift because false knock can occur from just about any metal on metal contact the sensor "hears" like a broken motor mount that torques at the shift point or the metal trans lines vibrating against the frame , just to name a couple. If you can find a nice long up hill stretch of road , get it up in 3rd gear and due a steady pull and try to not let it down shift,that should help eliminate things banging around while shifting . Check your fueling first though. Sam

 

[Pronto]

When it downshifted, did the tires spin?

 

[Pliskin1]

I asked about the shift because false knock can occur from just about any metal on metal contact the sensor "hears" like a broken motor mount that torques at the shift point or the metal trans lines vibrating against the frame , just to name a couple. If you can find a nice long up hill stretch of road , get it up in 3rd gear and due a steady pull and try to not let it down shift,that should help eliminate things banging around while shifting . Check your fueling first though.

I'll definitely get this done. Thanks for the info.

When it downshifted, did the tires spin?

I don't think so. At 35-40mph, I'm not sure my car has the ability to do that with the current set up. There's no serious mods to my car; all I think I've really done is freshen her up a little bit. That's part of the reason the knock is bothering me so much - with only minor tweaks here and there, I wonder why it happened. (Sam's comments noted above).

I know I need to be smart in general with the car, but is it OK to drive as long as it doesn't throw any more readings like that? Is 10.1 considered "bad", even if it was a false knock?

 

[Pronto]

Definately the goal is 0 knock. Doesn't always happen. If it does happen enough there will be damage. If you can hear knock inside the car while getting on it it's probably too late. That's why we have a knock sensor, to hear long before our ears do. If you can drive around normally and not have knock and only got it with that downshift it may be something hitting.

 

[SHADOWII]

Being new to these cars, it's difficult to catch all the info needed to answer the questions for diagnosis. If you could have seen the tach spike up, even tho not listening for the tire chirp/burn, it could have indicated the false knock. All my cars would break the tires loose rolling @ 45mph w/only the addition of a k&n filter.(assuming your trans is still good)
Did you tap the f/p reg. to see if the gauge would go back to the original setting? If it does, then the gauge is only good to tell you it has fuel pressure. If it stays at the 29-30#s, it may be nothing more than the diaphragm, being new has stretched a little. My first adjustable reg. did the same thing. I re-adjusted it to the correct poundage and never had a problem w/it since. That also could have been the source of your knock.
Several venders offer an extension kit for the f/p gauge to take it off the fuel rail and move it to the fender or back of the hood to tape it to the windshield for troubleshooting.
Try resetting the f/p and take another pass to determine if this was the source of the knock, while listening for tire chirp or monitoring the rpms.

 

[Pronto]

Do not trust the "turbo gauge". Get a real boost gauge and you can monitor rpms on the Scanmaster. The stock gauge is useless.

 

[TurboTdr3.8]

Has the TT chip been adjusted for WOT , timing and fuel ?

 

[psycho6cyl]

what fpr are you running? some people have had problems of pressure dropping off w the accufab units. 789 i dont think is terrible. get a boost guage and a known working fuel press guage and see what happens. did you change new w filter w lines?

 

[TurboBuRick]

789mv is right where you want to be. Try and do a third gear pull without downshifting and see if it retards.

Rick

 

[Pliskin1]

Just getting a chance to sign on here:

@SHADOW - I did not tap the FPR or re-adjust it yet. I'm going to recheck it, but timing won't allow me to do this until later this week. As for trans: it was fully serviced back in March, and we did modify the 1st and 2nd gear accumulator for firmer shifts. However, I did unplug the TC solenoid about 500 miles ago as it was acting "sketchy" and hunting for gears. Unplugging it eliminated the hunting. I realize my rpms will probably run about 500 higher on the highway, but I seldom drive on the highway. Most of my driving to date has been short blasts on regular roads. I have not changed the TC solenoid yet.

@Pronto - I do have an aftermarket, pillar mounted boost gauge, which I trust (hope!) is accurate. I've never relied on the stock one.

@TurboTDR - When I first got the car back in February, all the mods in my sig were done at the same time (except the exhaust) and the chip was done by TT. I would certainly assume it was done to operate at WOT. Not being sarcastic, but why wouldn't it be done to operate at WOT?

@psycho6 - My FPR, according to the liquid filled gauge I have on there, was showing about 30# (warm/hot) after this knock occurred. When we first set the FP, it was done with the car warm, vac off set at 43, and with vac on it went to 38. I did let the car idle this morning for about 5-6 minutes, and the FP was showing right around 37-38. I'm not sure if I need to actually drive to get an accurate reading, but I was curious what it was going to show after sitting overnight. I'm not familiar with accufab units? As far as fuel system: pump, feeder and filter were all replaced in March 2014, and have less than 800 miles on them. Tank is relatively new (couple years) and clean (and was drained anyway in March). Just recently changed 2 fuel lines (I think its the feed?), but its the one that runs up through the frame on the drivers side. Mine was old and rusty, and since I was doing all new S/S brake lines, I figured this was a good time to replace the fuel lines as well.

@TurboBuRick - As you and the other gentleman mentioned, I will get out there and doing the 3rd gear pull Being in Jersey, there aren't many places that afford me open road, so I'll have to hit the highway in order to this. There's no place close by me I can roll into WOT in 3rd gear without going to jail. Maybe a stupid question, but is there a good speed to be traveling in 3rd gear where I can get into WOT without downshifting? Should I be doing 50? 60?

Just a quick summary: Bought this car in February from original owner. 50,100 original miles (got all the paperwork). I put ZERO miles on it prior to having all work shown in my sig done by Jim Dunn (sans exhaust). Had my daily mechanic do the exhaust and rear main seal. For the last several hundred miles, no issues with the way the car was running, never a knock, but biggest issue was that I only had 11#s of boost (and I don't have a cat on, so it seemed reasonable that it was a fuel delivery issue or a problem with the wastegate). When my power master failed on me a couple weeks ago, I figured its time for the next set of repairs. So I got the vacuum unit, G body pedal, proportioning valve, replaced every brake line on the car, and the 2 fuel lines (tank to filter, and filter up to engine) and, of course, the FPR and wastegate. Car has 50,800 miles on it as of today.

Thank you all for your help so far and putting this into a language that I can understand. Man I hate being an idiot when it comes to mechanical "stuff".

Mike

 

[TurboTdr3.8]

Notes:
If the battery or ECM is disconnected, the memory will be erased and your settings will be lost (they
will return to the default 128). I recommend periodically looking at the saved values to make sure they
have been retained. Sometimes bad battery cables, a bad starter, bad ignition switch, etc. can cause
the ECM to lose its memory when starting the car.

This is what I am talking about you need to fine tune your chip to run it WOT , you can set the fuel and timing at WOT , my chip is programed from TT but under defaults settings 128 my car will KR if I do not adjust it . Just a suggestion because of your KR , little as taking your battery loose and not remembering to set it back .

 

[GNONYX]

I think what psycho6 was asking is what is the name brand of the adjustable pressure regulator you are using?
Is it possible to take a picture of it so we can help you to identify it?

 

[87-WE2]

My 3-2 downshift won't happen above 65 mph. That's where I used to start all my 3rd gear pulls. Now I go from a dead stop thru 3rd to get the o2 sensor hot.

 

[TurboBuRick]

Between 45 and 50

 

[Pliskin1]

Notes:
If the battery or ECM is disconnected, the memory will be erased and your settings will be lost (they
will return to the default 128). I recommend periodically looking at the saved values to make sure they
have been retained. Sometimes bad battery cables, a bad starter, bad ignition switch, etc. can cause
the ECM to lose its memory when starting the car.

This is what I am talking about you need to fine tune your chip to run it WOT , you can set the fuel and timing at WOT , my chip is programed from TT but under defaults settings 128 my car will KR if I do not adjust it . Just a suggestion because of your KR , little as taking your battery loose and not remembering to set it back .

I understand what you are saying, but I have no idea about how to look/recall the saved values? I am not sure if my battery went dead while it was in the shop over the last 2 weeks or so (I think the hood was left open overnight once, so perhaps the underhood light drained the battery enough?)

@GNONYX - The FPR is from Kirban. I don't know what brand they use.

General question regarding the 3rd gear pull: Should I have the trans in drive or OD?

Thanks again, guys.