for some reason
my car idles perfect at 1100 rpm but i had it set to 1300 but when for some reason it drops to 800 or 900 rpm it gets shaky... the shifter shaked back and forth... and with the a/c on forget it!!!!!!!! i have to rev it up so it get get up to 1300 again i think its a vacuum leak because when i step on the brakes the idle goes down to 1100... can anybody please help me?? ive heard of stuck bac's? or vdi's?? wtf are those?? aslo they told me to adjust the tps.. and i did and it brung the rpms down to regular normal engine speed .. and it still shakes... can anyone help me!

 

i had a similar problem this weekend. mine did the same thing as yours, and was hard to start too. my problem was ignition. i am assuming that all your ignition components are in good shape before applying my resolution to your porblem. mine was a bad leading sparkplug on rotor 2. i found it with a timing light. all other sparks looked very good, but it just didnt look right. it didnt fire all the time. i had an old set of plugs and replaced it. the problem went away, and the car ran great again.

 

another guy on here kind had your same problem. i think it was "dcrews"...anyway, he worked on it a bit, normal stuff liek plugs, even replaced the crank angle sensor. he said it idled kinda rough....

then last night i got an IM from him saying that he put 2 bottles of fuel injector cleaner in it, filled it up with some 93 octane...drove it for a while...and now its perfect again....lol, go figure...(this was on a 91 n/a)


what year car do you have? can you check the codes...it could be timing like rotorhead said...

 

My car has just started to play up to, it will Idle allright then for no reson the revs will drop to around 250rpm and it's also a pain to start.

We have just had some very heavy rain do you think that the Plugs, Leads etc might be damp? i have empted a can of WD40 into the leads and most of the Electrical plugs but its still doing it.

Do you think it may be the Tips? its just funny how other people have the simalar problems and it ends up being somthing simple (I hope)

O yeh mine is a 1990 T2

 

erik and rotorhead thanx for the info.. but when i got the car.. i changed the plugs..... and the old ones werent that bad... maybe it could be a spark plug wire? but then again erik it could be dirty injectors.. ive never ran fi injector cleaner.. so ill try that though... by the way erik... ur car looks almost the same as mines.. i got the same rims... i just need that turbo II hood of urs and the front lip.. which im desperatly lookin for!!!!!! lol thanx for the help guys

 

another question too?? does everybody run 92 or 93 octane?? i mean i know for turbo .. its a must so no detonation would occur? but for a stock 91? can we run 87? octane??? could that be the idling problem?

 

yeah, i've been running 87 octane for a while...it burns quicker...cheaper. might give a tad better throttle response...thats all mazda suggests for the n/a......

...for my T2 i usually run 93 or 94

 

greeeeeeeeeeeaaaaaat cuz i been runnin that all along!!!!!! hahaha
over here in florida its about 95 cent a gallon for 87 octane about 110 for 93.. but times are rough!!!

 

I'm no great mechanic but... the brake system can affect idle, through a vacuum leak. Check for leaks near the brake booster diaphram. Just a thought to part of the problem. I'm having my own idle problems