lizzard

Upon medium to heavy breaking in firsr gear the engine RPM drops to around 200 and occasiionally stalls.

I'll give you the senario:

Accelerate in first gear to 4000 Rpm depress the clutch and step hard on the brakes...not hard enough for the ABS to kick in. The RPM drops to around 200 and then recovers to 850 - 900. This is a new occurence. The Autometer AFR is behaving as it normally would, so I tend not to think that it is the Mass Airflow Sensor but I may be wrong. Possibly the fuel filter?

Any ideas any one please...

Thanks

submannz

Could be a vacuum problem, the brake booster under hard braking is using most of the vacuum in the circuit.

JIM THEO

I had this problem in my previous car - Almera GT - and the cause was a step motor, not sure about yours!
JIM

lizzard

Thanks submannz, but how do I fix it ? And pardon my ignorance, but what is a step motor?

Mad4it

Lizard - Not guaranteed, but it may well be worth adjusting the pre load on the Dump Valve.

peccy

sounds like the problem im am now getting, have you got a dump valve?, i only got this problem after having one fitted.

Mad4it

With the dump valve, you have to undo the nut, and adjust the thread with a flat head screw driver, to which ever way suits your motors tickover.

lizzard

No dump valve guys. Mods include Dawes, ITG filter and Denso Iridum plugs. Could it possibly be the fuel filter? Dont want to have to buy one unless necessary. The car idles perfectly except under the conditions given... pulls as it should under power also

jabroni

hate to say this m8 but see my thread it sounds like the MAF prob that i have good luck

submannz

The Dawes may need adjusting due to not closing fast enough when you brake hard, causing too much vacuum bleed from the vacuum lines.

Could also be the MAF sensor.

Also the Throttle Position Sensor.

It would be a good idea to check your plugs to see if they are the right colour.

[Edited by submannz - 9/5/2002 3:34:04 AM]

[Edited by submannz - 9/5/2002 3:35:54 AM]

scoobyslut

go for "MAF" or Mass Air Flow Sensor, had problem on my old mota, not a cheapitem, but needed to cure it or it even stalls out on you at islands etc.

scobymars

look under drivetrain section (no morehesitation problem or something like that) some guy seems to have same problem and he cleaned the isc valve and no more problem

scoobyslut

** If you do attempt to clean "ISC" valve, please dont use "brake cleaner", it eats the rubber seals inside, as I found out to my pockets demise and local garages enjoyment!
Sorry dont have a suggestion as to what to clean it with, does anyone else??
Then I'll know next time too..

Stuart Taylor

Spray carburetor Cleaner into the valve.

Stuart