2.0 D4d Stutter/hesitation - Suggestions Please

[Avalon]

After a little advice from those who've experienced this on possible solutions, i've done a bit of background reading of older threads so i've covered some of the basics.

I'm all of 500 miles back in a Rav after 7 years of various other cars and it looks like I have the dreaded stutter. Car starts, idles and pulls away fine but seems to make boost at 2.3k ish, you can feel it surge forward briefly, but then it seems to drop power slightly, then looses it followed by the same again a few hundred rpm later. Car has FSH from main dealer since new apart from last two services that were done at a local independent and the file of paperwork is literally an inch thick, if it needed doing it was done.

The background is when I got the car (before the issue) it threw a P1251 code at me after I put my foot down following collecting it, I pulled over, re-started and it was fine though the MIL stayed on. I drove it home gently home, checked the DTC and cleared it assuming it was a MAF issue and as I was planning on a full overhaul at 100k I added a MAF to the list of bits I planned to overhaul at 100k. Given the mileage and age I decided to run down the tank to 1/2 and add some BP Ultimate for the high detergent, idea being i'd clean up the injectors etc. and hopefully I could avoid having to strip them and go the ultrasonic route as part of the 100k overhaul. The car seemed fine, but i'd been taking it easy and avoiding harsh acceleration, it got a nice 170 mile run which I figured would allow the fuel to start to do it's thing and give the CAT a decent chance to get up to temp as it had only seen short runs recently. Up till this point i'd not noticed the judder but it did seem slightly down on power.

I then dug out my (old) Dragon Performance box from my last Rav (same engine but 53 plate rather than 55), it's an intercooler off job so I fitted it but left the unit without power assuming it would work as stock until I could open the unit and check the jumpers were at default etc. It was after fitting this that I noticed the issue so the first thoughts were either it's the box (i'd pulled the fuse on it so it's not powered/running bypass) or more likely i've not tightened up the intercooler hoses or have a boos leak on a vac hose. I can't find a split/worn hose so re-torqued the jubilee clips and made a not to replace them with marine grade SS versions.

So my plan is to remove the Dragon box, as it's without the fuse i'm not convinced it has anything to do with the situation but it removes a variable, replace the old jubilee clips with wider stainless steel version for a better seal and re-check all the vac hoses etc. I've already cleaned the MAF and EGR (it really wasn't bad considering the mileage/age) and checked the piston moves, I didn't strip the control unit on the top of the valve body - should I have? Until I can data log and see what the MAF is sending to the ECU i'm in the dark. Next up will be the fuel filter and investigate the SCV's. The paperwork showed it had the 'Governor Kit' which I believe is the pump and SCV's? this was supplied and fitted for £200ish +VAT (and got a £100 dealer contribution) at 58k, i'd assume the PCM update was applied at the same time and starting/idle seems fine, is it likely that the revised versions would fail again in less than 40K? Am I missing something obvious? As it's not a starting issue i'm ignoring things like glow plugs etc. as it doesn't seem related.

The elephant in the room is the turbo, obviously i'd rather do the low cost stuff first and get some live data logging before I go down that route so any suggestions would be appreciated.

Thanks :)

[sich1]

i have those symptoms every 9-12 months or so.

when you go on a long run 100+ mles stick a tin of bg244 or archoil 6600 turbo cleaner through the tank.

works for me! but all cars are different.good luck. let us know how it goes.

[Avalon]

Thanks Sich1, i'll give it a shot. I'd much rather fix the problem if i'm honest than treat the symptoms, but at this stage any improvement is better than no improvement. I've got a decent 80+ mile run to do either this w/e or next so i'll it in a full tank and see if things improve. Have you investigated the cause of yours or just learned to live with it?

[sich1]

pretty sure its carbon build up on the variable vanes in the turbo, but iam no mechanic!

if 80 mile dont put it through a full tank as it will dilute it. have a read of the instructuions on the tin.

half tank will be fine......get it hot and vary the throttle after the first 30 miles. good luck. let us know how it went.

[Avalon]

Just noticed the fuel filter is due every 40k/4yrs, the 80k and 90k services were both done by a local independent and the filter in place is a Toyota branded item from memory, no indy will choose genuine parts on a filter unless it's a dealer only part as they buy through factors (VAG Group being a possible exception as they outsourced the parts distribution to a 3rd party) so i'd expect MAN or Bosch, Blue Print or at worst Crossland if they're using cheap crap (ECP own brand - outsourced to the lowest bidder like the Eicher brand they own), without checking the paperwork i'm assuming it will have last been done at the 40k service by Toyota so it's now pushing 150% of mileage rating and at least the same on the age rating, I may be snatching at straws here but if nothing else it's past due so i'll grab one and see how that goes.

Also ordered the BG244, i'll run the tank down and do the fuel filter first as if it is that then at least I can report back on the actual fix.

[Avalon]

Update: Fixed.

Stripped/cleaned full intake system, checked and put back together, removed Dragon box, did an oil/filter change (3k early but peace of mind) and did the fuel filter.

The fuel filter had more crap trapped than I would expect for a car that had run clean fuel from reputable garages, also a coating of brown sludge on the lower level sensor. Given the surface corrosion, state of the filter element, amount of crap that came out when draining it/colour and sludge/deposits on the dirty end I'm blaming the previous garage who serviced it. It shouldn't look like that after 17k but the garage concerned is no longer trading so options are limited.

It now engages and pulls smoothly, or at least as smoothly as it should considering what it is. I'll run a full tank of BP Ultimate/Shell Nitro through again and see how it goes. Hopefully now it's had the EGR cleaned, new fuel filter, oil/filters done and a full tank of decent fuel through it should be problem free.

[sich1]

great news.

what is the lower level sensor you speak of? not sure which one that is!

is it the water in fuel sensor on the bottom of the filter?

[Avalon]

Haynes described it as the fuel level sensor from memory, but yes it's the plastic unit on the bottom of the fuel filter with captive float, the bottom plate was brown and the diesel that came out had a lot of small debris in it. At a guess me putting in BP ultimate may have made the problem worse, I specifically chose it over Shell etc. due to packing 5x the detergent of BP regular diesel but in hind sight anything in the fuel system that had built up over the last decade may well have been softened, detached and pulled through to the filter which ties in with what I experienced as it was a few hundred miles in before I noticed the issue.

Either way I'm happy it's back to being smooth, Friday was a low point as going up hill it was gutless. Now got 3k to get the stuff ready for the 100k overhaul :)

[sich1]

grats, job done