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jaybird1

Loss In Power Avensis D4D Mar 2000

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Avensis d4d Mar2002. I have read many of the posts and used the advice without solving the problem. Power loss occurs over 2500rpm in all gears apart from first, if the accelerator is slowly pressed then the car will eventuallty gain speed. Cruising at the national speed limilt is no problem, but over taking is hopeless at any speed requiring an excess of 2500rpm, but power up to 2500is fine and there are no starting issues.

I have checked the turbo waste gate and it appears to be free as are the vanes

I have checked the VRV electrically, no continuity to the body, and the resistance readings are with in the range given by Igor 37-44ohms, but I think the air flow in the diagram is wrong and should read air flows from port E to G and when the VRV isactivated should flow from port E to the filter

The SCV's are measuring 0.3ohms in excess, that is 2.0 ohms each instead of 1.7ohms. with no continuity to ground

I have renewed the air filter and cleaned both the EGR and the MAP flow

I also use BG244 every 10,000mls service, which previously resolved supermarket fuel problems and the fuel filter was replaced 30,000mls ago

Any advice would be greatly appreciated

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1. Check for air leaks on the intake side especially the higher pressure pipes after the turbo and up to the throttle, give them all a good tug to make sure they are tightly fitted as it is not uncommon for a hose to slide off under pressure only to reseat itself when the pressure drops.

2. At 30,000 miles the fuel filter is getting on, replace it with a new one

3. Have the ECU read for fault codes and at the same time have them look at the target fuel pressure compared to the actual fuel pressure whilst driving the car, as the car is accelerated the target pressure should shoot up and the actual pressure should quickly follow. if it doesn't then fit new SCV's.

Beyond that all I can recommend is find a local diesel specialist and let them have a look.

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Thanks for the reply. Have checked all hoses, all tight. By the way no smoke of any colour. Booked car in for diagnostic check on Friday to local independant and by then will have fitted new filter. I will pass on your remarks re scv's

New filter fitted with some small improvement, suggesting that there is a fuel issue

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Further to the aformentioned. Having lubricated the waste gate spindle, changed the air and fuel filters, checked the resistances of the VRV and SCV's and cleaned the EGR without success, I took the car into my local independant, Right Cars Saltcoats. They checked for fault codes and found one for the MAFF, which isn't surprising as I ran the car with it disconnected, and one referring to "technical help" ?

They cleared the codes road tested and found no fault. It would appear that clearing the codes and the work I had done resolved the power loss issue. Car running great now

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Good work getting this fixed. I'm sure there is something going on with the fuel filters on the D4D's. I had a random loss of power followed by engine shut down. I did some research and came to the conclusion that the SCV was a likely cause. Changed the fuel filter as a cheap 1st step and, hey presto, problem solved. Perhaps if the fuel filter gets a bit clogged it creates too much resistance for the SCV. I don't know for sure but there seem to be a number of power loss issues that are resolved by a fuel filter change - yours is the latest one I have seen.

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I think that coupled with clearing the fault codes, as although there was an improvement after the filter change there was no marked improvement until the codes were cleared

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Yep, that would be right. People talk about fault codes putting the car in 'limp mode'. Mine certainly ran very underpowered and then seemed to re-learn that it was ok to produce more power. Something to do with modern ECUs I'm told.

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Update on the power loss.

Power loss back again, fitted new SCV's problem now resolved, obtained valves from Toyota Kingco ? anyway cost £260, could have fitted myself but due to the screws being so tight left it to my great independant local garage "Rightcars of Saltcoats" who did the job for £42.00. Found out after buying the valves could have got them for £70 cheaper on ebay though don't know whether there would be a 5 year warranty as there is with the Toyota parts

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Hmmm. Reckon I may have to source some SCVs before the winter gets here. My problem seems very similar and only occurs in winter.

Glad you are all sorted now - and a big thumbs up to your local mechanics!

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1.

2.

3. Have the ECU read for fault codes and at the same time have them look at the target fuel pressure compared to the actual fuel pressure whilst driving the car, as the car is accelerated the target pressure should shoot up and the actual pressure should quickly follow. if it doesn't then fit new SCV's.

Devon Aygo, do you know what is acceptable difference between the target fuel pressure and the actual fuel pressure. I can see pressures on my 2.0 D-4D Avensis (Techstream) but always the actual one is lower (especially idling). Fore example: warm engine idling - 32000KPa and 30900KPa, Warm again 2000 revs (static), - 58400 and 58000.

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I have a yaris 1.4D4d with the same issue. I cleaned EGR, catalytic etc etc. I noticed that upon removing the vacuum tube from the wastegate the problem disappear. Obviously it will become 1.4 no turbo but having said this I am now suspecting that the fault is something related to the turbo boost. All hoses are ok. I am suspecting that there is something wrong with the waste gate. Any suggestions?

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