Rebuilt 1JZ won't accelerate properly

[Sam]

My JZA70 Supra melted 2 pistons in August of 2009. It's been in the shop ever since being rebuilt.

The rebuild was completed, but annoyingly, many many issues keep coming up that prevent the car from behaving normally! I can delve into those issues in another post you guys want to hear about it or if you think it may serve as clues for the current issue.

So the car won't accelerate. I have an aftermarket adjustable fuel pressure regulator (I don't recall the brand right now, it's all at the shop. The device is purple and has red plugs on it. It looks to be designed for a V engine with 2 fuel rails, so we plugged the unnecessary ports), and the engine will start, idle cleanly, and drive at a slow rate at about 20-25 PSI of fuel pressure (at idle, the fuel gauge is only in on the FPR itself, so we cannot see what kind of pressure is being made while driving). The AEM wideband gives a reading of around 14.5 at idle at 20-25 PSI of pressure.

So what the car does when you try to accelerate at a quicker pace is stutter and backfire, and the wideband gives a lean readout, often so lean it's off the charts and cannot give a number. Either there is such a massive amount of fuel entering the chambers that it alll cannot be burned and gives the wideband a lean reading, or the vehicle is actually being starved of fuel for some reason.

So the mechanic turns up the pressure incrementally. He reaches 35 PSI at idle on the FPR, but now the car wants to flood when you first start it up. If you press the accelerator right after you start it up, it won't flood too much and the idle will stabilize. The mixture at idle at this point is either off the charts rich, or at around 10 - 11. The vehicle is able to drive somewhat normally at this point, but extremely rich. This will not do. I want it to drive and behave normally while I break it in.

Here is a list of modifications/stock items:
-Stock ECU (Had a blitz unit previously, but it fried. It is blamed for the demise of the engine)
-SAFC II (not connected currently)
-370cc injectors currently installed (Had 440cc in combination with the Blitz ECU and SAFC II in 2009. But removed for rebuild since we were eliminating the aftermarket electronics for the break-in period)
-HKS timing gears (each set to 0)
-264 BC cams
-Walbro 255lph fuel pump
-Aftermarket FPR (I'll update later with pictures and brand another day)
-Deleted the fuel dampener
-Driftmotion single turbo kit (60-1 / .72 AR) (upgraded FMIC) (HKS blow off valve) (full 3" exhaust)
-Stock map sensor
-Stock 02 sensor (had to make custom bung as Driftmotion kit lacked one)

That's all I can think of right now in regard to the engine. I've read on here some people that have had similar issues as mine. One guy had a kink in the fuel line going from the hanger to the filter, another put the fuel dampener back in and magically solved the issue.

I told my mechanic about these stories and is sure that there isn't a kink in any of the lines (he put in the Walbro himself about a year ago) and he doesn't see the fuel dampener doing anything to help since it only smooths out and restricts some gas flow. But if he cannot figure it out, I will ask him to try putting the dampener back in anyways to see what happens.

It should also be noted that I have another stock FPR. I bought the aftermarket unit because the car was idling and running extremely rich and it was thought that the stock FPR was not working. I bought the aftermarket unit and awhile after, another used stock FPR here on Supramania, just in case this would happen. Again, if he can't figure this out in a timely fashion, I'll have him try the stock until.

This car is BEYOND frustrating!!!

If it runs properly again, my goals are to buy a full standalone ECU (haven't decided on what yet) and 680cc injectors (or larger). I want to reach 500rwhp. I've already screwed myself financially with this car, what's the difference if I blow a little more on it.

If you guys have any suggestions or similar stories, please share! Thanks!

---------- Post added at 01:07 AM ---------- Previous post was at 01:04 AM ----------

I'll try and get video footage of the 1JZ and it's various faults on Monday! I'll also see what brand of FPR I have.

 

[IBoughtASupra]

Put the dampner in before doing anything. That should be the first thing that you do.

Second. You should be running a base fuel pressue of 40-50 PSI.

You are getting to much fuel, there is really no way you are going to have too much fuel and have the wideband read lean. If you have no fuel in a cylinder, then all the air will be unused and move to the wideband which will cause the lean reading. Are all the injectors in working order, check them to see if they were in spec?

A regulator has a feed and return port. Make sure you are using the feed and return ports correctly and not reseversed. You can always find which port is responsible by looking in the manual. If you don't have the manual online, just get the brand and model and Google can help with that.

If you jump the terminals for the fuel pump at the diagnostic block, FP and B+, you will run the pump at full 12 volts. You can do this to see if you have a restriction in the line that will cause low fuel pressure.

Do those things first and report back.

 

[Sam]

We have a constant 12 volts going to the fuel pump. During a previous issue where only a few driblets of gas could reach the engine, we did the 12 volt mod. As it turned out, there was a blockage in the fuel line. Then after that, the car ran way too rich. So then we reverted back to the 370cc injectors and still, the car ran way too rich. It would want to flood at at start up. The FPR was to blame, so I purchased that aftermarket unit.

I told the mechanic to put the fuel dampener back in and run a base pressure of 40-50 PSI. He still was skeptical, but agreed because he is also running out of ideas. Tomorrow I will return to the shop and try and remember to take pictures and maybe a video.

 

[mk3tattoos]

Ya it would help to know what afpr you have, it might be the wrong kind.

You also might need a new guy to work on your car.......just saying...

 

[IBoughtASupra]

Make sure you are using the feed and return on the regulator. They have specific ports.

 

[GrimJack]

Testing the fuel lines is easy... take off the fuel return line, bolt in a hose, put it in a bucket with a known volume, fire up the pump, and use a stopwatch to figure out if it's flowing properly.

Testing the FPR is pretty easy too. Take off the vacuum line and use a bicycle pump / dialed down air compressor to put in more pressure. Verify that the fuel pressure increases as the signal line pressure increases.

How did you decide the old ECU was responsible for the previous failure?

 

[Sam]

There was a blown capacitor and a burn on both sides of a circuit board in the Blitz Access ECU. Plus after replacing it with a stock ECU purchased from here, the car was able to start. I still have the Blitz ECU and I'll attempt to send it away to Driftmotion to see if it is repairable after I get my car running.

Oh and the blockage in the fuel line, as I stated before in a previous issue, was the fuel dampener itself. It was completely blocked up, so that's why the mechanic took it out to begin with. He cleaned and cleared it out of any debris and it ready to be put it again. I will return to his shop on Friday to see what the conclusion on that was.

Here are some photos of the MagnaFuel (apparently) Fuel Pressure Regulator. The part number is included. The mechanic is also certain he installed it correctly.

---------- Post added March 31st, 2011 at 12:06 AM ---------- Previous post was March 30th, 2011 at 11:59 PM ----------

As I recall, the steel line comes from the fuel rail and the rubber line on the top side of the unit, is the return. The large bolt was used as a plug for the secondary inlet.

 

[Sam]

Anyone else use MagnaFuel FPRs?

 

[IBoughtASupra]

I always use Areomotive.

It does not look like you have it hooked up correctly. Inlets from the return side is usually on the side and the return to the tank from the regulator is on the bottom.

I cannot tell from the picture how you have it hooked up since it is tilted. I don't trust any regulator besides Areomotive.

 

[aphxero]

It's worth a shot. Who's this mechanic?

fwiw under 600ish whp I usually use stock regulator or a sard/tomei. Always works well.

 

[Sam]

I always use Areomotive.

It does not look like you have it hooked up correctly. Inlets from the return side is usually on the side and the return to the tank from the regulator is on the bottom.

I cannot tell from the picture how you have it hooked up since it is tilted. I don't trust any regulator besides Areomotive.

After it's all bolted, the device is actually upside down. He did this because the supplied gauge wouldn't have been facing the correct way. The the adjustment is on the bottom and the return is on the top, but only because it's mounted upside down. I can double check the instructions, but I'm certain that the mechanic did it properly.

It's worth a shot. Who's this mechanic?

fwiw under 600ish whp I usually use stock regulator or a sard/tomei. Always works well.

I live in Bum-Fuck nowhere, so there was little opportunity to take my car to a proper JDM tuner shop type place. I would have to travel 8 hours to another Province for that (that's also what I did to get my car tuned, and had a horrible experience).

The Mechanic is a competent man and was happy to take on the project (most garages in this sort of hick town dislike my car and are afraid to work on it). He worked at a Nissan Dealership here in my hometown for much the 80's and 90's, so he's well versed in Japanese turbo charged cars. He would tell me of the 300ZX's and whatnot that would come in to get their engine's rebuilt. So Now he runs his own shop, but unfortunately it is also busiest place in town, so he doesn't work on my car terribly often.

He just cleared the hoist bay today, so on Monday he hopes to have the fuel dampener in. And if that doesn't work, there is still the second stock FPR I bought here on Supramania we can try out. But by the way everything seems to work for my automobile, nothing will work.

 

[enjoi.this]

Have you replaced the fuel filter yet?

 

[GrimJack]

Have you replaced the fuel filter yet?

Why replace it? They're a bitch to get at, and testing it on the car is a 10 minute job at most.

The tests I suggested in post #6 are well worthwhile.

 

[Sam]

Yeah, new fuel filter and new Wablro 255 lph pump. The pump has been tested and it operates normally (with the constant 12v modification).

 

[1jzdarek]

Is ur TPS set correctly? if not it can cause it to run super rich,best way to tell, they are usually always set to middle.Look at the 2 TPS adjusting screws see if its in the middle if not,set it to middle see if the car runs better and try to adjust the fuel pressure.

 

[IBoughtASupra]

Any update? Did you install the dampner yet?

 

[Sam]

Thanks for the suggestion 1jzdarek! I will inform my mechanic about adjusting the Throttle Position Sensor!

Yeah, he cleaned out the fuel dampener and put it back in. Apparently it was the source of the clogged fuel line previously and is why he removed it. It had a fair amount of debris in it! He raised the fuel pressure to 38-39 PSI and let me go for a drive. He didn't get around to swapping out the older spark plugs though. So when I drove the car, it still sputtered and missed frequently, especially from idle to about 2,500 rpm. Gentle acceleration after that is fine. However, if you start to approach positive boost, the engine will start to stutter and miss again. But not always. It still wants to flood itself on cold start ups, but on hot start ups, it can start with little drama.

I'm really hoping those plugs are fouled and that the replacements will help. This idea of the throttle position sensor also seems like a logical idea.

Years ago, I went to Calgary, Alberta to get my car tuned. I went to a shop called "Auto Dream" but they had no idea what they were doing, they were all a bunch of kids. I had my 264 cams, springs and retainers, and some 440cc injectors installed. However, when I got it back it appeared to be slightly slower than when I brought it in. I only dyno'd 293 rwhp.... They didn't even gap the cam shims at all. And after that, the car always had a hard time starting (like it does now). And it ran pig rich all the time (even thought I had a SAFC II to easily compensate for the slight increase in injector size). I think what Dale and I are solving now is because of what that shop did to my car.

 

[1jzdarek]

The plugs will be fouled for sure,adjust tps if its not put new plugs try rasing the fuel pressure and take it for a test drive.

 

[Sam]

I talked to Dale the mechanic today as he was leaving the shop. He was busy and was not able to really work on my car today. He has the plugs ready to put in and took a gander at the TPS. He says it does not appear to be tampered with. But he also did not play with it. He said he can hook up a volt-meter to it to be certain that it is producing correct voltages from idle to wide open throttle.

I hope he finds out something. I'll go back again on Monday (which is also my 23rd Birthday!).

 

[IBoughtASupra]

Updates?