Insane detonation after LA3 swap

[litdog]

I have an 84 SVO, only mods are LA3, 35# injectors, 86 single fuel pump, and a K&N

I had been running with the 35# injectors and the stock 84 computer, and it ran ok, but wasnt too exciting.

I just installed my LA3 I got per instructions I found online, and it idles great, and runs smooth. Problem is, now in 3rd and 4th gear as soon as I start getting into boost (1-2 lbs or so) I hear an insane amount of rattle/detonation (knock sensor unhooked, I always shut down right when I start to hear anything)... Fuel selector set on regular, 91 octane gas from 7-11 (only option at the time, may have a lot to do with it). I just replaced the fuel filter, and the base timing is set at factory spec and all ignition is in good condition as far as I can tell.

Here are the codes I just pulled:
54 - Intake Air Temperature sensor circuit open; VAM sensor out of range (I was getting this before the LA3 swap sometimes)
81 - new after LA3 swap
82 - same (emissions stuff?)
83 - same

10

53 - TPS?
54 - same as above

Any ideas? I doubt it's the fuel system since it didn't detonate like this before the LA3 swap, but I suppose it's a possibility because of the extra fuel the 35#s would have added with the stock 84 computer helping equalize it out...

[litdog]

I don't get on it much in first because I can't shift into second above a certain RPM/speed without insane grinding, but second gear seems to be fine all the way up to 10psi... maybe it's not really detonation and it's a transmission noise, but it sure sounds like detonation.

EGR system as far as I know is still functional and complete. Is there an easy way to unplug it to see if it makes a difference? Still seems like that would cause detonation under boost in all gears. It doesnt idle really beautifully 100% of the time, but it's rather smooth. Every now and then i'll hit the clutch and gas just right at a light to ease up and it'll try to die for a second.

I checked to see if the resistor wire was still on the fuel pump wiring from the single pump swap and has been spliced with normal wire to a body ground.

Timing is set at 5-6 degrees BTDC with the spout unconnected, so i'll put that back to the stock 10. Seems like it was set at 10 last time I checked it, but maybe i'm thinking of the escort. My roommate just got out here in the garage to work on his 280z, so i'll steal my fuel pressure gauge back and check that.

I'm wondering about the TPS code and the VAM/IAT code. Possibly the problem there somewhere? I don't know why it only would detonate in third/4th, at least at such low boost compared to second gear with no detonation up to 10psi. I'll drive downtown and put a few gallons of 101 octane in with the 91 and see if it goes away later, and check my fuel pressure.

[litdog]

Just put my fuel pressure gauge on and turned the key, pressure spiked to 50psi and then dropped to 0 in about 5 seconds with the engine not running, so apprently my fuel system doesnt hold pressure I think i'll just get a good fuel pump and AFPR and forget about it

[litdog]

Fuel pressure at idle:
39 PSI vacuum line on
46 PSI vacuum line off

[litdog]

Stock cam, stock engine. Only mods are a K&N, LA3, 35# injectors, removed the stock boost control and put in a manual boost valve, and an 86 fuel pump as far as I know. If the pressure is too high, there must be some sort of problem with the fpr or return line then. Ill look into that.

18 inches of vacuum according to my Autometer boost and vacuum gauge

[litdog]

Should I have removed the boost control box next to the VAM under the hood?

[Mr. Pink]

Disregard....

[svoman2300]

Are you able to check the fuel pressure when you are driving? Is it a new fuel pump or used? Most of the codes are normal after an LA3 swap, except for the VAM and tps codes. I would check those before you go any further.

[litdog]

TPS was .91 throttle closed and 5.07 WOT, seemed to go scmooth through the whole range, but I can only see so much with my digital multimeter

I havent been able to check fuel pressure while I am driving yet because of how the hood is on these cars... I can't just stick it up out the back and under the windshield wiper... quite annoying

Also from what i've read the ACT/VAM thing may be normal since I didnt hook up/add a temp sensor?

[turbo2.3stang]

The TPS should be set between .95 and 1 volt. If your timing is off set that back to 10 btdc. I also think youre supposed to disconnect the box that the boost control solenoid is connected to. Codes 81, 82, and 83 are normal after the swap because I have had those on two or three LA3's. The fuel pressure should be 39 with the line OFF and around 32 with the line on.

[litdog]

There is a brass looking thing that the fuel line goes into to the right of the intake before it goes to the fuel rail. It has one rounded side and a bolt/screw sticking out of it. What does this do? Any sort of adjustment?

I'll reset the TPS, I had just heard over .90 and below 1 volt was where you wanted to be. Timing is being set back from 6 to 10 btdc

[turbo2.3stang]

I dont know what that is supposed to do. Mine never did anything when I unscrewed it all the way or turned it all the way in. What I ended up doing is replacing the svo lines with later metal lines with the newer fuel rail. The svo lines broke in like 3 or 4 different spots. So I got rid of that round metal thing.

[NavySVO]

There is a brass looking thing that the fuel line goes into to the right of the intake before it goes to the fuel rail. It has one rounded side and a bolt/screw sticking out of it. What does this do? Any sort of adjustment?

That is a fuel pulse dampner. It is there because the fuel pump is a reciprocating type pump, and will not deliver a smooth discharge like a gear type pump....like used on oil pumps.
With a "chug-chug" type delivery of the pump, the dampener is supposed to smooth out the flow to a steady state.
I believe the adjustment on it is not for raising or lowering pressure, but the amount of dampening it will do.

[litdog]

Alright, I set the base idle, tps to .92v closed, and finally to 4.65 WOT instead of 5.2v and set the timing to 10* BTDC. Idles better, but still have the detonation problem. There is no detonation in first at all, a little in the lower boost while the turbo is spooling in second.. just a tiny tiny bit. Then in third as soon as i hit boost it just goes crazy until i let off... My grand national acted like the svo does in second with a little knock while spooling, and the solution was to pull timing or put in a gallon of 101. I'll try going to the shell station and putting in 91 to see if that makes a difference, if not, i'll put in some 101 and see what happens.

Next thing i need to look into is the fuel pressure being high. The pump is a parts store stock replacement for an 86 svo/later 2.3/5.0 EFI according to autozone.

[litdog]

What kind of petrol are oyu running now? What worries me is the comment

"try going to the shell station and putting in 91 to see if that makes a difference"

Are you running 87? Not good.

I'm running 91, always have, just it's from the 7-11 because it was much cheaper when i was running almost no boost. I know better than to run 87... I wish it was that easy though, cause that would be my problem