Wierdness

[pizza boy]

Been experiencing misfires etc when putting the car under load. It pointed to the usual suspects...dizzy/rotor/plugs. Checked dizzy and it looks shot..heavy deposits on all 4 contacts. So im ordering new items of all three.

The wierd thing was..when I started my car (a very troubled start I should add)the idle was as usual lumpy BUT when I stabbed the throttle the engine revs dropped to 200rpm and went very quiete....and all I could hear was my induction kit sucking in air and the boost gauge winding up and down from 0 to 1.5 Bar! AND the revs moving up to 2000rpm and down to 200rpm all on its own without me touching the throttle! WTF?! Looking back at it it was pretty comedy.

Questions:

What the hell would cause this reaction from the car?

Also is it normal for dizzys to be eaten in 12 months?

[jaxx]

possible that you might have a dodgy earth somewhere

[pizza boy]

Actually it wasnt 1.5bar it was about 0.7 it went up to. Dodgy earth? Hm interesting as my remote sensor for my alarm has also stopped workin have to manually arm it with the keypad now BAH!

[msherry21]

Ah its stuffed Pizza face! sell it and get a red one! you know it makes sense!

sorry for the pointless post.

Michael.

[pizza boy]

Up yours! Hey mike I might need to borrow your dizzy for an hour I got an mot on friday!. Thats if mrT doesnt deliver in time. Ill pay ya!

[jaxx]

just a random thought dude, first thing i concider whenever i encounter electrical gremlins. can be anything from a split wire to water vapour in the wrong places?

[DeusMR2]

leak in intake/intercooler/throttle body pipes? leak in boost guage pipe if its mechanical?

also throttle position sensor is known for being a bit temperamental on our cars

what i dont get is how the boost guage managed to read positive pressure when idle!! max it should reach is 0 under idle afaik...

[System~G]

Chances are it's not the dizzy, rotor, sparks or leads. Although it won't hurt replacing them if they have done more than 25000 miles - but that's a lot of mileage for 12 months use B)

You need to look at the MAP/MAF/MAS sensor and make sure it's clean (dust and moisture free) and connecting properly. The sensor itself could also be knackered.

Make sure the air filter is clean and not getting wet.

Also look at the pipes relating to airflow - make sure they're not cracked/leaking.

Lastly, look at the fuel system. When was the last time the fuel filter was replaced? It could also possibly be clogged injectors. That Redex stuff is quite good for cleaning fuel systems.

The symptoms you describe sounds like the engine is getting incorrect fuel/air mixture.

[Fitz]

I'd go with deus, check the intake pipework. My celica had a split in it but I never spotted it myself. It was right on the side and ticked over fine, but as soon as you touched the throttle, the engine twisted which opened up the split. This made the car almost stall and then run irraticly as the sensors were reading too much air and making all sorts of adjustments.

[Jimlad]

well my motor is gonna get booked in to the garage for a vacum test, just to check everything. Rico gave the car a quick inspection and found a cracked hose straight away. Replaced this, but there could easily be more.

[pizza boy]

Yea good point guys I should check all the hoses make sure all is ok there and sensors. I should also point out that one time I ran outta fuel very recently (dont laugh!) I was literally 100 yards from the Shell station too! And the car conked out..I started it again and heard a huge KabooM! There mustve been all sorts of cr@p sucked into the engine...I crawled to the station and filled up and it was fine. That was only last week it must be related. But the erratic misfiring has been going on for a month now but I can imagine the above incident helpin doh!

I shall be buyin some redex too to help clean the injectors out. Would octane booster be any help?

[pizza boy]

Hm replaced the dizzy and the rotor arm. Its still happening.

Heres what happens : The car on cold start up will idle low at 950-1000..not 1500 like it should.

It'll stay like that for around 30sec. Then there will be a wierd "brrmp brrmp brrrmp" sounds interrupting the steady "brmmmmmm" of the engine and the idle judders about with this sound

If I tap the throttle there is a clear delay befor the revs will respond and it has a lot of trouble settling down again.

Eventually itll conk out.

Ive checked the hosing they are all fine. Ive yet to put in the redex stuff. Im gonna go out an buy it now. Its so annoying as this happened to me last year and upon replacing the dizzy rotor it was fine. I was sure this would sort it but apparently not. What could be wrong with it?

[pizza boy]

Also where is the map sensor located?

[mattmr2]

You want to be checking for fault codes now really - it sounds like it could be a temp sensor thats gone..... I'm gonna guess at fault code 21.... but i bet i'm wrong.

The map sensor is the little black box thing behind the inlet manifold next to the diagnosticis bay.

Matt.

[Stef Derner]

I hear the knock sensor is quite delicate and the kaboom you mention could have buggered it. If the timing is being messed with due to the ECU thinking it's seeing knock, it could have this sort of effect.

[houston]

"ahem" i have a knock sensor if u need one? unused

[pizza boy]

--------------------------------------------------------------------------------

Heh thanks for the kind offer Houston but tis ok! Its sorted!

Its strange last time i replaced the dizzy and rotor+plugs the problem dissappeared instantly the minute I fired the engine up. This time however the engine fired up and was still %$(ed BUT...after writing up this topic I started it again and it sounded ok...I let it idle till it was fully warmed up..still ok.

Drove it for 2 hours after..mixed drivin and the problem is gone. It seems the ecu and sensors took a little while longer to adjust to the new dizzy than last time giving the initial impression that the problem was still there. So its sorted itself out and settled down eventually thank %$(.

Thanks for the tho guys ...I never realised theres so many bluddy sensors that can knock idle off !

But it appears that this was yet another dizzy/rotor/plugs=misfiring escapade...oh will it ever end..

All the best for the new year :group-cuddles:

[DeusMR2]

glad its all sorted dude