mg zt 1.8 turbo flat spot - Page 2

francoh20 · 30th March 2010, 15:46

is that the sensor that is next to the air filter box?

Cymrudragon · 30th March 2010, 16:05

Quote:

Originally Posted by francoh20

can anyone help? when i go to really gun my 1.8 turbo it developes this annoying flat spot between 3000 and 4000 rpm its starts to chug like the fuel is being shut off or something, if however if i press throttle slowly and steady up to speed it does not have it? ive tried everything i can think of. does anyone have any ideas???

What have you done to the engine, modifacations wise. need more info for a correct diagnoses.

Right. have you got a pressure gage? or boost gage. looking at what you have said, is this correct,
pressure @ 1.700 rpm ok
pressure @ 3000 rpm low if so have you atempted to alter the wastgate ? dont!!! prob set incorrect (wasgate actuator)

but as you are saying fuel it is possable that it has a week mix on load.

francoh20 · 30th March 2010, 16:12

ye ive got a boost gauge and the pressure is no different from normal. ive not altered waste gate. my vacume gauges are normal showing to. if i run with boost on or off it still does it when press throttle quickly. i also have a fse power valve so i can enrich fuel mixture or make it lean either way its still the same.

Departed 32016 · 30th March 2010, 16:16

Quote:

Originally Posted by francoh20

is that the sensor that is next to the air filter box?

yes that's the one, i had a similar problem on a bmw and changed this with a new one and cured it. Again i have heard of these being clogged up if you use an oiled filter such as a k+n

francoh20 · 30th March 2010, 16:20

well ive got ram cold air filter which is the same thing! il have a look and clean it out along with the others sensors tonight.

Cymrudragon · 30th March 2010, 16:44

Quote:

Originally Posted by francoh20

ye ive got a boost gauge and the pressure is no different from normal. ive not altered waste gate. my vacume gauges are normal showing to. if i run with boost on or off it still does it when press throttle quickly. i also have a fse power valve so i can enrich fuel mixture or make it lean either way its still the same.

As you can emagine not seeing the car in the flesh makes it difficult but i will have a go.

What is the boost pressure at 3000 rpm, take car for a run put it into 3rd
on full throttle, hold for 5 seconds and read the pressure @ 1750 rpm,IIRC is around the 0.5bars(3.6lb/2 and at 3000rpm 0.40 to 0.45(5.8 bar 5.8lb/2.

also check the injector flow if you have a power valve i think this is the prob as the ecu needs to balance the flow to each injector. highly recomend a flowcheck, you need a t4 i think unless there is away to find it useing the obc also you need the flow rate for you engine type iirc its around the 200/220cc/pm

francoh20 · 30th March 2010, 16:52

ok i will run it and check it tonight on way to work, ive had it plugged in before but it was coming up no fault. it was doing it before i put my powervalve on so i thought a powervalve would maybe cure it with all the mods ive got.

Cymrudragon · 30th March 2010, 17:24

Quote:

Originally Posted by francoh20

ok i will run it and check it tonight on way to work, ive had it plugged in before but it was coming up no fault. it was doing it before i put my powervalve on so i thought a powervalve would maybe cure it with all the mods ive got.

ok mate good luck also if you aint got enough to think about try the following

Coil pack
Divertor valve if fitted to 1.8
Fitted a LP-turbo will not get more power over 3000rpm
clutch slipping/worn
fuel/air mix
ign timing
low pressureat 3000rpm=wastgate fault
air leak
exhaust leak
intake blocked
throttle not opening/weakmix/incorrect mix
turbo us
wastgate not closing

francoh20 · 30th March 2010, 19:27

mmm maybe a coil pack oo something like that. think thats only thing ive not changed or checked yet! il have them out tonight to investagate. il be in touch. any ideas pab???

Synchromesh · 30th March 2010, 21:39

When I had a ZT 1.8T it would pitch violantly when it hit 4000rpm. I traced it to the pivot seizing where the waste gate actuator arm attaches to the waste gate. This stopped the actuator from opening the waste gate and the resulting overboost tripped the ignition cut out to protect the engine. I removed the spring clip and prised off the arm. I cleaned the pin and the hole and reassembled with a special high melting point anti seize spray. I also cycled the waste gate several times every few weeks. To do this I traced the small bore pipe from the waste gate actuator up to the ignition cut out (think it was on the battery box). I pulled the pipe off the cut out and carefully pressurised it with an electric tyre pump. You can just see the arm/wastegate if you look down from above. The arm will move across then stop the pump when the arm reaches the end of its travel. If you over pressurise you may rupture the diaphram in the actuator. It only took about 15-20 psi to reach full travel.

30th March 2010, 15:46	#11
francoh20 Avid contributor mg zt 1.8 turbo 160 Join Date: Jan 2010 Location: fauldhouse Posts: 174 Thanks: 0 Thanked 1 Time in 1 Post	is that the sensor that is next to the air filter box? __________________ [SIGPIC][/SIGPIC] possibly the lowest zt around?

30th March 2010, 16:12	#13
francoh20 Avid contributor mg zt 1.8 turbo 160 Join Date: Jan 2010 Location: fauldhouse Posts: 174 Thanks: 0 Thanked 1 Time in 1 Post	ye ive got a boost gauge and the pressure is no different from normal. ive not altered waste gate. my vacume gauges are normal showing to. if i run with boost on or off it still does it when press throttle quickly. i also have a fse power valve so i can enrich fuel mixture or make it lean either way its still the same. __________________ [SIGPIC][/SIGPIC] possibly the lowest zt around?

30th March 2010, 16:20	#15
francoh20 Avid contributor mg zt 1.8 turbo 160 Join Date: Jan 2010 Location: fauldhouse Posts: 174 Thanks: 0 Thanked 1 Time in 1 Post	well ive got ram cold air filter which is the same thing! il have a look and clean it out along with the others sensors tonight. __________________ [SIGPIC][/SIGPIC] possibly the lowest zt around?

30th March 2010, 16:52	#17
francoh20 Avid contributor mg zt 1.8 turbo 160 Join Date: Jan 2010 Location: fauldhouse Posts: 174 Thanks: 0 Thanked 1 Time in 1 Post	ok i will run it and check it tonight on way to work, ive had it plugged in before but it was coming up no fault. it was doing it before i put my powervalve on so i thought a powervalve would maybe cure it with all the mods ive got. __________________ [SIGPIC][/SIGPIC] possibly the lowest zt around?

30th March 2010, 19:27	#19
francoh20 Avid contributor mg zt 1.8 turbo 160 Join Date: Jan 2010 Location: fauldhouse Posts: 174 Thanks: 0 Thanked 1 Time in 1 Post	mmm maybe a coil pack oo something like that. think thats only thing ive not changed or checked yet! il have them out tonight to investagate. il be in touch. any ideas pab??? __________________ [SIGPIC][/SIGPIC] possibly the lowest zt around?

30th March 2010, 21:39	#20
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 624 Thanks: 50 Thanked 44 Times in 32 Posts	When I had a ZT 1.8T it would pitch violantly when it hit 4000rpm. I traced it to the pivot seizing where the waste gate actuator arm attaches to the waste gate. This stopped the actuator from opening the waste gate and the resulting overboost tripped the ignition cut out to protect the engine. I removed the spring clip and prised off the arm. I cleaned the pin and the hole and reassembled with a special high melting point anti seize spray. I also cycled the waste gate several times every few weeks. To do this I traced the small bore pipe from the waste gate actuator up to the ignition cut out (think it was on the battery box). I pulled the pipe off the cut out and carefully pressurised it with an electric tyre pump. You can just see the arm/wastegate if you look down from above. The arm will move across then stop the pump when the arm reaches the end of its travel. If you over pressurise you may rupture the diaphram in the actuator. It only took about 15-20 psi to reach full travel.