My car...bad moods! ?

[Bobfish]

My car gets in bad moods, i swear to god.

90% of the time she is fine, boosts and drives lovely. The other 10% of the time she just wont play ball, she bucks, and sometimes plain just doesnt accelerate. I get all of the noises i should get, and no untoward noises - i get a full 10psi of boost, but the car just doesnt go anywhere! I just accelerates really slow...its almost like its bogging, it only happens when i floor it - if i ease her up she is generally ok.

Does anyone have any idea what is causing this? its not boost control because as i say, i get 10psi of boost. Its not a boost leak because it only happens every now and then, and i removed all of my boost pipes today and refitted them (although i did find a small boost leak)

Please someone help me, its really getting on my tits!

Spec is standard bar apexi filters, HKS sqb BOV and magnecor 10mm leads....65k mile engine usually works well however recently blown a coolant seal. (did the o ring fix)

The car did do this before the coolant seal went though...so i guess thats kindof a red herring.

Any help appreciated! thanks

[Bobfish]

Ok, just went out and did quite a few boost tests.  It either sticks at 10 and goes nowhere, or spikes and surges around, sometimes up to 14 (but the car is still very slow)

could the car possibly be retarding the ignition timing or something because it is detecting a problem?

im guessing its time to remove the UIM and inspect the vac hoses/check valves...

[andrewrx7]

\'Fraid can\'t help you on the technical side, but it may be easier and quicker (and save you alot of hair!) to just take it along to one of the rotary garages and have it checked and diagnosed. I like to tamper as much as anyone, but these things are horrendously complicated and it may be better to just have someone who knows what they are doing look at it first?

[Bobfish]

Thanks for the input andrew, and thats for assuming that just because i do not instantly know what the problem is that i do not know what i am doing!!!!!!!!!!!!

on another note, I think i may have found something...


Was looking at the throttle body earlier, and noticed that my two throttle arms dont seem be moving in union... if i pull the throttle cable (or get someone to press the gas) the arm moves, but the one behind it stays still. THis should move shouldnt it?

This makes sense, as i would imagine this is what caused my boost pipe to pop off...

imagine this, all ports open on inlet, 10 psi of boost... 1 or two of them snap shut (how many does this secondary arm control?)

Boost goes through the roof and hose pops off. Lucky it wasnt my engine popping off! lol

[andrewrx7]

Thanks for the input andrew, and thats for assuming that just because i do not instantly know what the problem is that i do not know what i am doing!!!!!!!!!!!!

   Didn\'t mean to imply that you didn\'t know what you\'re doing! No offence intended! Just that on many forums (both sides of the Atlantic) there are always loads of people that like to get stuck in when a problem rears it ugly head ....then months later still have problems and get very p1ssed off with the car etc!

As for your throttle arms: the way you describe it, both mine move together (with the car off). Maybe you\'ve hit the problem quickly!

[Bobfish]

Thanks dude, can you see what it is that fixes them together?

oh, and np about the comment!

[goose]

Was looking at the throttle body earlier, and noticed that my two throttle arms dont seem be moving in union... if i pull the throttle cable (or get someone to press the gas) the arm moves, but the one behind it stays still. THis should move shouldnt it?

This is normal. I\'m not entirely sure why there are two arms - I guess there may be some sort of application which requires 2 throttle cables. You can check your butterflies are opening by taking off the elbow of course.

This makes sense, as i would imagine this is what caused my boost pipe to pop off...

imagine this, all ports open on inlet, 10 psi of boost... 1 or two of them snap shut (how many does this secondary arm control?)

Boost goes through the roof and hose pops off. Lucky it wasnt my engine popping off! lol

If the pipes on the pressure side of your inlet ducting are popping off, you\'ll need to make sure the clips are done up nice and tight - I\'ve got jubilee clips all round on mine.

A couple of things to check-

1) The double throttle control - is it opening up fully once the car is fully warmed up. (I\'ve removed mine!)

2) Are any of the vacuum control lines under the UIM splitting. 9 times out of 10 it\'ll be these little blighters which cause permanent or temporary problems which are hard to troubleshoot. Have the pipes ever been replaced?

[Bobfish]

ive been told the two arms are for cruise control operation, but ive also been told that both arms should move together and im sure mine used to!

The pressure side of my inlet popped off due to sudden massive increase in boost pressure due to sudden massive increase in resistance due to one of the throttle butterfly snapping shut.  Thats my theory!

I will check the double throttle control - whats the best way? Do you mean the arms SHOULD move together/ because mine never do, even with the car warmed up! how do i remove it?

Dont think the vac lines are splitting - theyve never been replaced, but i dont seem to have a boost problem; the car is regulating boost perfectly, i get a 10 8 10 pattern (most of the time) it just feels like the car isnt getting enough air! (i.e some of the throttle butterflys are closed)

Im going to take the elbow off tonight and check that, check my spark plugs and wires and reset my ecu - then ill let you all know how i got on...

Hope this gets sorted soon, ive only just sorted my leaky coolant seal!

[Bobfish]

thinking about it i think my car may already have been done, as i dont get the 3000rpm surge on my car.  I start it, it goes up to 2000 rpm then drops straight down to about 1200...

In any case, ill check it! been reading up on the dual throttle control system on rotormafia... first thing im going to check is my solenoid...sounds like it could be the cause.

[John Yorke]

If you have a cat it is most likely partialy blocked, when you nail it it cant cope with the extra exhaust.

[Bobfish]

I was thinking that John, but i would have thought this would be a slow occurance?

my car literally was very fast one day, and the day after it was sh*t slow...

[John Yorke]

I was thinking that John, but i would have thought this would be a slow occurance?

my car literally was very fast one day, and the day after it was sh*t slow...

It is quite possible that it has collapsed

[Bobfish]

oh really, how do i test it? remove the cat? haha.

seriously though, i cant afford a new cat if thats not what the problem is.

[John Yorke]

If you are generating 10 -14 psi of boost and your not loosing it logic dictates it is not passing through your engine the only real reason for this is some form of restriction on the exhaust side of things, I dont know your car but I\'m assuming it is fairly standard, 1st place I would look is the cat, take it of and have a poke around :p  Could always buy a de-cat pipe lot cheaper that a cat [and you get 15-20 bhp extra to boot :bandit ]

[Bobfish]

Boost is an indication of restriction to airflow, thats why i figured to check my throttle plates...but yes i should probably check my cat too.

Do these cars have the underbonnet pre cat like the US Models? mines a 92 FD jap import.

and yes the car is standard, it has apexi filters and a blitz boost gauge and thats it for engine mods (as far as i know)

the car was however run with a 1 piece catless racing exhaust (basically a piece of 4.5 inch metal pipe from the front to the back of the car) for a while i believe.  This was removed by the previous owner as it was too loud.

If i buy a de-cat wont i get boost creep?