Avensis '98 Hatch Seemingly Unsolvable Problem

[spysmasher1940]

Hi I am a new member and have joined in the hope of making contact/ or getting answers to a problem with my Avensis '98 hatch S reg. 7AFE 1.8 engine.

I've lived with this problem for quite a number of years since it is only a pain in the butt when doing motorway driving. When up to normal temperature,

that is maybe after 8-10mins the engine severely stutters when close to 3k revs in any gear, so accelerating is slow because I can only get to about 2700/

2800 revs before having to change up gear, otherwise the engine stutters. When doing normal urban driving and just cruising, anything from 30 to 50/60 mph depending what type of road I'm on it drives absolutlely sweetly after changing up gears before reaching 2800 revs. If I am on a clearway or motorway I can only cruise up to 2800revs before the engine starts stuttering, this is why any long distance driving is a pain now. I have been told this condition is known as LIMP MODE, whereby the ECU is informed by a sensor or component that something is wrong and it causes the fuel injection system to restrict fuel input when the engine revs reach 3k, although in my case it kicks in at 2700/2800 revs. I need to say at this point that when starting the engine at any time from cold ie morning or after long parking etc, It drives absolutely perfectly, by that I mean it goes to 5k revs if I want to accelerate that fast and behaves just like a normal engine, if I can get to the motorway quick enough I can drive at 80/90 mph or faster...................until the engine gets up to temperature and then the LIMP MODE immediately kicks in and I have to slow right down to 62/65mph. I have had 3 (THREE) diagnostics done, 2 by mobile tuning services and the last 1 was done by AUSTEC tuning just past Basingstoke on the M3 (J7), now these boys do high performance cars, rally cars, racing cars

and are ECU specialists, they have the best test equipment available and said to me on the phone we will sort it. Well they said costs were £97 an hour and that an hour was plenty of time to sort the problem, after 3 1/4 hours and 5 or 6 drive outs with two mechanics in the car, one the main man and one of his best men, I still had the problem. They detected it ok but just could not find the source, NOW SINCE THEN i have gone to a jap spares replaced the ECU,same problem, then swapped and tried other parts from an identical avensis that was in for scrap, HT leads, cam sensor, engine heat sensor and about three other sensors that I dont know the name of, and still the problem persists. The only one I havent tried is a long tubular one that goes into the manifold ( looks about the same size as a pencil) and I have been told it measures gases in the exhaust or something like that. During all 3 diagnostics testings all the sensors were thoroughly tested and all came up as functioning properly, even when the diagnostic equipment was all linked up to everything and then the engine revved to 3k, to the stuttering point, they came up clean and on the right diagnostic the you could see the fuel injection system flat-lining. So thats the story.............I just need an answer.

[jamesholden]

This is probably too simple to be the answer but I thought i'd mention it. Getting the correct type of spark plugs is critical on the lean-burn engines. The engines run pretty hot and normal spark plugs can't take the heat and can cause rough running.

[t-spiritpete]

This is probably too simple to be the answer but I thought i'd mention it. Getting the correct type of spark plugs is critical on the lean-burn engines. The engines run pretty hot and normal spark plugs can't take the heat and can cause rough running.

I agree with James on this one (sometimes the simple things are missed) and it is so easy to check and replace them if required, even an expert might miss this one just assuming the correct plugs are fitted.

Pete.

[spysmasher1940]

This is probably too simple to be the answer but I thought i'd mention it. Getting the correct type of spark plugs is critical on the lean-burn engines. The engines run pretty hot and normal spark plugs can't take the heat and can cause rough running.

I agree with James on this one (sometimes the simple things are missed) and it is so easy to check and replace them if required, even an expert might miss this one just assuming the correct plugs are fitted.

Pete.

[spysmasher1940]

Thank you both for your suggestion regarding the spark plugs, but looking back on my records I had new Iridium plugs fitted in 04 at 58kmiles and the problem started in Sept 07 at 78k miles, only 20k into the service book life of 60k for this type of plug. The plugs were taken out and looked at when the various diagnostic tests were done and they looked ok and put back in. To add to my first account, because it runs perfectly until reaching normal temperature then limp mode kicks in, I/we can assume ( alright I know this is obvious ) it is a heat related problem unless told otherwise. So there is something that is breaking down doing its required function when the revs get to 27/2800k, but works perfectly at say 2500 revs when you can cruise all day long and wouldnt know anything was wrong. By having this rev restriction enforced on me I am getting good m.p.g, but sometimes we all like to go fast !!

The difficult thing with motorway driving is that I dont have the revs to overtake anything, I have to stay in the inside lane with the artics and large vans that are invariably travelling at 55-60 mph and sometimes I cant keep up with them, so they are overtaking me. If left to cool ie parked for a period of time, cant say how long cos never really checked, then driving of again is perfect until getting to normal temp, and then it starts again. I hope you dont mind me trying to give you guys a clearer picture. It seems as though something is breaking down under load ( 2800k revs ) but absolutely fine below that. Get those deerstalkers out of the cupboards cos this is a mystery.

[caveman_si]

Bizar as it sounds check the air hoses. Check they are all ok and not touching something hot.

Warm air pipes collapseing under load was prob on a friends car (non toyota) a few yrs back, was a right pain to diagnose. Similar issues used to falter once warm and you gave it some beans but under partial load was ok.

[jimrotts]

is the vehicle manual or automatic

if automatic if a problem with gearbox will put vehicle into limp home and may have to goto toyota as alot of garage readers cannot access gearbox ecu's hope this helps

[dibber]

Sounds like it is engine load related. Might be worth looking at fuel and electrics first as they both can create load related faults.

[Beagh1958]

To spysmasher1940.

As above postings suggest, keep it simple for now. Plugs, compression test, pipes collapsing underload, loose connections ie: earth leads etc etc. Stick your hand over rear exhaust and see what your back pressure is like, should want to blow your hand away. Valve clearances from cold should be inlet 0.15-0.25 mm & 0.25-0.35 mm for exhaust, might be worth a check as a last resort, bet the cam cover has never been off, unless you know otherwise.

Good luck & regards, Beagh.

PS: The rule of KISS is needed before coughing up anymore money to the techies. The only jobs i ever had remotely like this, firstly was a blocked exhaust & secondly a naff distributor which showed no flash codes. Keep us informed.

[Reelemin.lk]

I had a similar problem some years ago guessing you have fixed this long ago was wondering what you found ? My problem was a faulty coil.Was fine cold but when it got hot it broke down electrically,was a real pain . Cheers

[Pat2u]

Sounds very much like the coil or condenser to myself both will create the limp mode syndrome, on older vehicles it will tell tale with exhaust backfires.