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HELP! Inconsistent acceleration, rpm gauge jumps down and then up - prado 2001

Hi everybody,

I hope somebody can point me in the right direction.

I thought I sorted my car's fault when I changed the throttle pedal but the fault is back and a lot worse. Im using techstream and it is showing a fuel rail pressure of 45 Mpa at idle but drops to 26 Mpa at full throttle. The car can only do 2000 rpm and 30MPH. I measured the fuel return line flow rate and it takes three minutes to fill a one liter bottle at idle. Is this normal??? No fuel leak from the injector return line and no leak from the fuel rail relief valve. All the leak off is coming from the pump overflow port. at first, I concluded that the pump is shagged but when I did a fuel leak test with techstream, the fuel rail pressure can go up to 120Mpa. The injector readings are spot on.

The car starts at the button, no misfires, no smoke, no fault codes, new SCV, new filters.

Thanks
 
Are you 100% sure the rest you ran confirms the pump is in good health? At idle with no load the pumps maybe can produce good pressure but just as it showed, when you want to actually move the pressure drops.

If the pumps in good health, it would point to a ECU failure of some sort. Alternatively, if your initial code was the throttle related it would make sense that maybe that has failed and is given a lower reading than what you are asking for, which is limiting your speed.

Cant give you a factual response, but with my KZ engine, I'm pretty certain I'll get a liter of fuel off the return line in well under 1 minute, probably half of that if I had to guess, if not less. I'd think with those even higher pressure pumps, it should be considerably more.
 
Old post I know.
Was keen to see if the original poster was still around and whether there was any resolution on this issue.
I’m running a 1KD with a similar issue that I’ve spent heaps of time and money on trying to resolve…..alas, no success as yet.
 
I'm not an expert, but from the various posts here on the subject, the ones that have ongoing and difficult to solve issues are autos. I have replaced SCVs twice in my manual kd engine, and that has brought it back to new both times. (I've done it twice because of galactic mileage as opposed to any ongoing issue, they are known to fail around 125-150,000 miles)

I wonder is it something to to with the tps and how it might be different on an auto
 
@Bob
Thanks for the response.
I’ve done the SCV (brand new) and whilst slightly more responsive, didn’t solve the issue.
I went straight for the TPS after that, which I think is integrated within the throttle body. I swapped a whole throttle body in from another vehicle - again no change at all. I hope I got this right?

Am getting a bit desperate to solve as it is driving me crazy. I posted a full summary of my journey so far into this forum just last night.
Am particularly keen to locate peeps who have had similar issues and their resolutions.
 
Open your fuel cap and make it air tight with a plastic bag . pull the return pipe off the fuel tank and have someone pump like a mad man primining the fuel filter until you get a diesel shower while refitting the pipe to the tank .

Worth a try , it costs nothing and it cured some erratic fuel problems in my 1kz-te .
 
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Any updates?. It looks like I have a similar issue. only now it went all in limp mode. No codes.
 
Hi team and also @Icebaby - I did find a fix and ended up posting my solution under another thread. Solved due to great inputs from the other members.

In my case I was getting good linear rpm through to about 2100rpm and then a bunch of surging and loss of power overall.

I ended up replacing my MAF sensor with one from another vehicle it totally fixed my issues.
My MAF was delivering incorrect readings to the ECU at particular flow rates, which then caused air and fuel delivery problems (resulting in surging). It seems that MAF’s can partially work, with some flow rates being better than others!!!

My MAF was clean as, just unable to function correctly at all flow ranges.

I didn’t read all the detail within, but please also do check the MAP filter (that it is clean and not cracked) as this can also cause erratic issues.

I hope this helps in some way.
Chris.
 
This was a schematic I found that was useful in describing some of the key ECU inputs associated with the fuel delivery system.
I worked my way through this list.
 

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