knock at wot

[jay dcpt]

Any input would be greatly appreciated. Heres my setup on the car from what i can see. I bought just like this and it will knock at wot the guy i bought it off of wasnt able to get it right and sold it to me. 87 gn pete tomka cold air intake, what appears to be a ta49 turbo and everything else on the car appears to be stock ic, injectors. fuel reg etc hooked a scanner up to it a took it on the freeway this is what i got when it starts knockin. BLM is 142-145, ect is 187, intergrator is 128 knock signal is yes maf is 128g\s air temp is 54 deg o2 volts 0.15 o2 cc is 6 sparkadvance is 23deg tps is 3.31volts. No i do not have an aftermarket boost gauge i will be getting one next week until then wich way do i turn the adjustable wastegate rod to lower the boost until i get my boost gauge installed i think this is a maijor part of the problem. also after a while of cruising the car can get as hot as 194degrees is this to hot should i install a 160stat? The car has 100 000 miles at 1\2 throttle the car will take off like crazy while cruising on the freeway at wot when the factory boost gauge pegs it will knock if i get out of it and keep the boost out of the red on the factory gauge which i no is unreliable the car is actually pretty damn fast Sorry about the lengthy thread. Any input?

 

[bmackinnon]

It's bad, bad lean and about to blow headgaskets if you keep dogging it in this condition. Lengthen the actuator rod to lower the boost. You need to install a fp gage with an extension hose that you can tape to the windshield while you go for a drive and verify that fuel pressure is rising lb. for lb. with boost, and not dropping off at wot. Do some poking around and figure out if it has the stock fuel pump and wiring. If so, first thing to do is replace the pump with a modern high output unit and upgrade the pump wiring with a hotwire setup.... these mods are absolutely mandatory with even a completely stock setup.... the factory pump was marginal at best brand new, and over time, becomes very weak..... you will also want to install an adjustable fp regulator, a modern chip (turbotweak ftw), and preferably a scanmaster so you can keep an eye on the important parameters (02 and Knock Retard) at all times... Please don't run the car hard until you get a handle on things and do a bunch of reading here and the 'spring cleaning' at Turbo Regal Web Site... which also has a ton of helpful tech information... your wallet will thank you!!:wink:

 

[GNVYUS 1]

Don't got WOT until you have done these things

1) Get an adjustable fuel pressure regulator (AFPR), adjust your base pressure to 42psi with the line off and see if your BLM's come down to 128.
2) Adjust TPS to read 3.8 or higher at WOT, do this with the key on (not running) and floor it to see where you're at, then adjust the TPS and do it again. Loosen the bolts and generally you can just lean it back to gain the top end reading you need. Make sure your base TPS reading is around .42.
3) Boost Gauge for sure, the factory read out is sad.
4) Every turn counter clockwise on the adjustable wastegate rod is about 1psi less. With the stock IC and an O2 count around 780 at WOT in 3rd, you might be able to run 14psi on 93 octane with ZERO knock if your timing is 23 degrees up top.

Putting a 160 thermo won't make the car run cooler, you probably need an upgraded fan to keep it around the thermo's temp just to start. If that's the stock rad, then the core is in some need of a good cleaning for sure, let alone maybe a recore. RMI 25 can kill a lot of crude in the core so that might be a good place to start.

 

[jay dcpt]

Brian can you tell that i am running lean by my blm readings? From what i have been reading if my blm is around 128 + or- 10 this is where i want to be My short term fuel is always there at wot or just cruising and at cruising my long term is within those specs as well just not at wot Just curiouse if that reading was what made you say that. From what i can see the fuel reg is stock along with injectors and i dont see any additional wiring that would indicate a hotwire setup. spring cleaning has been done. I will run down to the shop tommorow morning and grab a fuel gauge and post my readings but as for tonight i will lengthen the rod a bit to keep the boost from climbing and i could tell when i drove it home after buying it that it would detonate at wot so i have not been beating on it hard at all yet. Also when you look at o2 readings what numbers do u like to see? I was basically just looking to see if my numbers were switching back and forth wich they are at idle so i figured the o2 was working and doing its job. Is 0.15 considered lean at wot? thanks for the help

 

[jay dcpt]

Thanks dr booster i will order up an adjustable reg tomorrow i see kirban has a billet one for a little over a hundered bucks is there one that u suggest? Or does anybody on here have one they want to sell?... And what is rmi25 id imagine its some type of cooling system conditioner / cleaner? I have never heard of it where can i get it? Once again fellas i cant thank you enough for the help.

 

[Hacksaw]

Brian can you tell that i am running lean by my blm readings?

Yes:

Quick Reference Page For the '86/'87 Turbo Regals and '89 Turbo T/A

http://www.gnttype.org/images/blmint.gif

A lean mixture WILL make detonation & overheating worse!!

The factory boost "gauge" is worthless for diagnosing problems.

I'm still learning bits here & there about these, but GNVYUS 1 has some very good ideas.

What octane fuel are you running?

 

[jay dcpt]

Thanks for the info hacksaw. Im going to post some fuel psi readings tomorrow and i run 93 octane gas with a stock chip

 

[bmackinnon]

I said bad lean due to the O2 voltage = 0.15 v = 150 mv... You want to see 760-780 mv wot at the top of 3rd gear (max load) to be safe. What scanner are you using? I seem to recall that some of the old OTC's use a stoich reference of 500 mv as opposed to the 450 mv reference we are used to... and shown in the previous link.... you may want to verify that with your scanner documentation, as with a .500 ref, you would want the scanner to read even higher.... like 900 ish as I vaguely recall. Also, saw where your scanner showed knock "yes"... which doesn't give the amount of timing retard (knock retard - KR)... just so you know, ideally you want to tune for ZERO KR, along with the above mentioned o2 voltage... although a degree or 2 is acceptable, especially at the shifts, for instance... damage is being done WAY before you can hear audible knock.... I think the consensus is that our cars are generally pulling ~15-16 deg KR before you hear it 'pinging'... and that's way bad... just for your reference.... would be nice to know how MUCH knock you are getting... or maybe not!!! :wink:

 

[bmackinnon]

As gnvyus said, you need to adjust the tps so you get more voltage wot... he said 3.8v+, but really you want more like 4.5v wot... it's an long standing debate whether you really need that much, and I don't think you do, but it's usually achievable (or real close) without any problem, and 4.5v wot IS the factory service manual spec.... so you might as well adjust it to get all you can out of it and then have no worries with respect to that..:wink:

 

[Hacksaw]

Also, that turbo probably needs bigger injectors, a bigger fuel pump, and a chip to adjust the WOT fuel curve. Though, nothing about a chip mentioned here for that model of Turbo:

http://www.gnttype.org/techarea/pictureguides/turboguide/turbos.html

As I recall, the ECM ignores the O2 sensor input at WOT, since it should be around an air-fuel ratio of 11.5:1 with everything stock. But, the O2 readings are of value for a scanner. At those O2 sensor readings you gave, like maybe 15:1? (!!), you're into the danger zone for WOT!!

A mechanical boost gauge will tell you if they went too crazy with the boost.

Also, is the fuel filter new?

 

[TurboBuRick]

Check the vacuum lines on the wastegate. If they have any holes, you will over boost and knock knock.

The other guys have good advice as well.

 

[jay dcpt]

Well last night i reset the iac then reajusted the tps so my wot values are above 4 volts i also lengthened the wastegate rod 4 turns to be safe. took it out and i was able to get on it and stay on it untill basically top speed with no knock at all but you could tell that the car was making way less boost thats the first time since ive owned that ive been able to get it that fast without knockin. yes my fuel filter is brand new and my vaccum lines going to wastegate are all good. The Scanner i am using is a otc genesis with 3.0 software bmackinnon i will find out if i can get a actual reading with it for kr instead of just yes or no and i will find out what the stoich ref is for the o2 readings. The weather up here is crappy today so no fuel pressure readings today. And it looks like i have an afpr coming from another member here on the board. And I should have the boost gauge in next week some time. So its slowly starting to come together thanks again guys for the help im sure you will be hearing about this car again as soon as we have a nice day again i will let you guys no my fuel psi and would appreciate your suggestions.

 

[bmackinnon]

Good deal! Once you get the boost gage and fp gage hooked up and verify fp is rising in a 1:1 ratio with boost, then you can start sneaking the boost back up 1 lb at a time until your 02's and KR signal that's all she can handle at your octane level in the tank.... nice work...

 

[berserker6]

in his initial post he stated at WOT he was seeing 128gs AF. anyone else think he may have an MAF going bad and leaning the motor out?

 

[bmackinnon]

in his initial post he stated at WOT he was seeing 128gs AF. anyone else think he may have an MAF going bad and leaning the motor out?

I saw that too, but I took his post to mean that was the MAF reading when it started knocking like hell.... I'm assuming he was hearing the knock and letting off... he stated that he couldn't come anywhere near keeping it nailed all the way up due to (assumed audible) knock... having backed off the boost and alleviated the knock, it sounds logical... probably started knocking like hell into 2nd gear and above.... and the 128 g/s reading makes sense at that level... my take on it... and he seems to have a handle on it now..

But good lookin' out berserker! OP - max maf output is 255.... you 'probably' won't get there with your setup right now (low-ish boost), but you should be seeing MAF output of 200ish+ g/s at wot, top of 3rd gear.... if it's not close to that number, we need to know, because obviously, the maf number is the primary fueling input, and if it's low, then the fueling will reflect that.... and cause a lean condition... another knowledge point for ya'! :smile:

 

[jay dcpt]

bmackinnon i believe you are correct with your statement about my maf readings that is when i had my foot in it and it was knockin. With key on engine off my maf reading i believe was 3 or 4 g/s then with engine running it went to 6 or 7 and the went up accordingly as i accelerated. And from what ive been reading those are correct numbers to see which leads me to believe that my maf is functioning properly. Another crap day here today in Cleveland so no fuel readings today but tomorrow is suposed to be a nice one. I will let you guys no the fuel readings as soon as I can. I want to see myself as well. It really makes you feel good when you start to sort out the gremlins in the car and you can take it out and feel the improvement It would of taken a hell of a lot longer without your guys help thanks

 

[bmackinnon]

It really makes you feel good when you start to sort out the gremlins in the car and you can take it out and feel the improvement It would of taken a hell of a lot longer without your guys help thanks

True that! :biggrin: That's what this board is for!! Welcome to the darkside!

 

[GNVYUS 1]

The base MAF reading has no bearing on the WOT reading, so it can easily be really off yet function fine at idle (like 6-7 is). Before I switched to the Z06 the Remanned Maf wasn't going over 248 at WOT yet the car ran great everywhere else.

When you take it out again, keep an eye on this and report back. It should go to 255 pretty fast once the pedal is mashed.

 

[bmackinnon]

The base MAF reading has no bearing on the WOT reading, so it can easily be really off yet function fine at idle (like 6-7 is). Before I switched to the Z06 the Remanned Maf wasn't going over 248 at WOT yet the car ran great everywhere else.

When you take it out again, keep an eye on this and report back. It should go to 255 pretty fast once the pedal is mashed.

That's not really right. It won't go 255 with a stock-ish setup at 12-13 psi boost... it might get close, but won't get there at that level... but you are right, it should be watched to make sure the readings are logical... I don't think it should be reading 3-4 g/s without the engine running, and 6-7 g/s idling is right on the edge of too high.... should be more like 4-6 idling... I'd agree the maf is slightly suspect and deserves a close eye....

 

[berserker6]

any progress jay?