Save my engine fom detonation Please!

[jeffp]

The fuel pressue is normally set to 3 bar for the sport 400 package, the sport 450 package is set to 4 bar for additional flow to get the added hp, along with a differently tuned program.

So it would stand to reason that your idle would get rich increasing the fuel pressure.

[Bernardd]

Sorry Scotti GNZ' date=' yes they are aftermarket Bosch but they were in before this round of mods and worked fine at 37psi like JWT recomended. I have not yet tried 43psi yet I have not had much time to mess with the car, maybe I'll try that tomorrow. Thanks for the suggestion.

Bernardd, its a yellow/white wire #5 that goes to the transistor thingy at the coil, I had my Apexi hooked to that for tach signal then it went away when I hooked up my MSD. What is the CAS? is that the disc in the dist with all the slots in it? While driving the car tonight if I hit 14psi at low revs like under 3500 it does not det but as the revs pass 4500 it dets for 1/2-1 sec then goes away, don't know if that helps. I wish I could get it on a dyno and see my afr and timing are doing but I don't have the cash for that right now. Can someone lay on my fender and shoot the timing light while I do a 3rd gear pull?[/quote']

 

Fly me down and I'll hold the timing light.!! Better yet, I'll have software and hardware for watching the maps in realtime in the next while. You'll still have to fly me down to use it. When you mention that the pinging comes in and disappears around 4500 you might want to try seafoam. Afshin had good results with fixing up that problem. CAS is the disc in the distributor.

[Scottie-GNZ]

So let me see if I have this correct. You have aftermarket injs that are supposed to be set at 43psi. JWT says it is OK to run them at 37psi and you are running lean on boost. Hmmm. You realize that running those 420s at 37# makes them more like 390 or less and somewhat unpredictable? So, you up the FP and the boost problem improves (the idle is understandable as Jeff said). I wonder why they told you that and what other compromises did they make in that program.

 

I would stop giving things a try such gapping plugs at .025, fiddling with static timing without knowing how that affects the timing map they built, etc, etc. Let them correct the fueling for the injectors you bought at the FP the injs were designed to run.

[datsunan]

Yeh I wish that was an option, although I live in the next town over from JWT I have asked if they would help me out with this and they said they don't work on customers cars. They have a dyno but only use it for R and D. The thing is I use to be able to run these inj at 37 off my stock rail as high as 17psi boost and had no problem. New DP and JSK rail and aeromotive FPR and now I have this problem. I could not adjust my fp before and did not need to. These upgrades were suposed to make the car run better not give me more issues, its so frustrating to invest time and money and go backward on performance. Update on det, drove the car during the day at 20deg timing and 44psi and it does not det as loud but it is a bit longer now. Does not det in 1st or 2nd but longer pulls in 3rd-5th. Idle continues to get worse. I will pic up some Seafoam but I don't think it will help in the long run.

[Scottie-GNZ]

JWT does not need the car to fix the problem. They need to reprogram the chip. Assuming the FP is unchanged, then the only thing you added that might have an effect is the DP. Like headers on a N/A, a more efficient DP could cause the engine to run leaner because of the more efficient scavenging and less backpressure. What you are experiencing in 3rd vs 1st/2nd is normal. The engine is under more load in 3rd.

 

You need to give JWT a detailed description of exactly what the car is doing and let them reprogram accordingly. Hopefully this is a part of the service you paid for. That is how it works with systems like that. You have to go back to the chip burner every time you make a change on the fly. With programmable you make the changes accordingly on the fly. One of the reasons I like the SDS so much is because of the "WHAT IF?" knob (Rich/Lean knob to SDSers ) where you would simply richen or lean the mixture when you have a problem and based on the engine reacts to the knob, you adjust the fuel or timing map accordingly.

 

I know that does not help you much, but you are completely reliant on the chip burner to guesstimate what your engine will do. BTW, I know you say you are running 20* timing but that is really a meaningless number when you are in boost. What matters is what JWT put in for full advance and retard as boost increases. Do not get frustrated, just work with them to reprogram based on the problems you are having.

[VinhZXT]

How about go back to what you have before and add one thing at a time and see which item actually caused it to ping. Basically baseline your system before adding more variables to the equation. That seems logical and alot easier than to mess around with your injectors or fuel maps or ECU..

[frank280zx]

actually knocking is also variable to external temprature gas etc. also it can start knocking when driven at a constant speed where you are close to 'max out' short burst of extreme boost dont neccary mean knocking as longer cycles on teh same boost might

 

but im with Vhin on this go back to basic take it from there

[datsunan]

Scottie Gnz you are right on the money! I went to Jwt today brought the car down and once someone saw it pull up they came out of another car to talk to me. this guy told me exactly what I had suspected, that the problem I was experiencing is dew to the DP making the engine breath better. Same as what you just said. The problem is as he explained and as you had said earlier, you (I) don't know what is happening in the engine. And as Bernardd stated I need to buy a wideband 02. JWT also said I should buy the Innovative Data aquisition device so I can log whats happening. then and only then will the be willing to help me out. $100 dollars buys me a chip of what changes I ask them to make. Again Bernard is right I need to buy the batronix programmer. And on and on and on .............. Thanks for the help guys you are an asset too this sight! Ps the guy who filled my head with knowledge was Jim the man himself. If I did'nt know any better I would think you guys work for JWT. JK

[Afshin]

I find it odd that the car went from 15-16 psi and no detonation to 10 psi with detonation because of the better breathing and less backpressure from the new downpipe. Specially when as Bernard pointed out JWT usually run on the rich side with AFR’s in the 10’s on boost. Even if the car was is now in the 11-12 afr’s because of the downpipe…..it should not detonate at 10 intercooled psi.

I still agree with all that has been said, however I would suggest you try a few things first and systematically before you get your hands on a wideband O2 and the rest. My recommendation would be, in order:

 

-Use up the gas in your car and fill her up from another station. Bad gas really does happen, and it could cause your problem.

-Clean the ecu/efi connectors and so on.. it is a old Z after all

-Re-gap plugs around .25-.30

-Use the seafoam (I know that is not the main problem, but it has the potential of significantly helping, should you have carbon deposits..)

-Drive the car and see how she does.

-Then increase fuel pressure in step. Never fully trust a new gauge, my brand new autometer fuel gauge reads 5 psi high so 40 is actually 35….. Keep making it richer by increasing psi by 3-4 lbs and then drive it and see if the detonation goes away. I f it is running rich and still detonating, it is less likely to be from fuel and JWT code. You changed the fuel regulator, so maybe this is your problem.

-Then retard timing a few degree and see if still knock, then retard another few degree and test it again…., then you will have a idea about potential timing problem

 

It won’t cost you anything to try these, and at the end you may end up figuring out the problem or at least better ruling out potential sources for the premature detonation.

[VinhZXT]

This start to sound like a Nissan dealer tech. Since they know you put in the new downpipe they have to come up with the reason "Oh your car breath better now so it detonate and you have to buy a new chip".. That's a load of BS.. Do they know you also put in a few other new items? Yeah buy another chip that should fix your problem. lol... Sound just like the dealer... Doesn't it? It doesn't take a genious to figure out your probem. How many people in here had upgraded their exhaust system to 3" and had any problems? None so far. I doubt it your fuel rail. Let try another FPR first what do you think? sorry I had to vent... For something like this you need to take 1 step back before go forward and that is go back to what you know worked and then take 1 step at a time and add 1 thing at a time and test it out. Is that logical ?

[Doug71zt]

How do you have your new fuel rail and regulator set up? Is the regulator on the supply side of the rail, or on the return side? I had a look at the pictures on you other thread, and I wasn't able to tell. The fuel system should go pump-rail-regulator-return. If you are dead-ending the rail, you are going to have fuelling problems on the Zcar.

 

Just throwing out some ideas here

 

Doug