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Discussion Starter · #1 ·
hi all,

i have ventured this question before but no one seems to be able to answer it (gauntlet thrown to the floor).

the red auto 6 has a prob. in neutral or park, tickover is just over 1000 revs. in drive (any selection) it ticks over at about 600 revs. surely, tickover should be the same in neutral or drive? its not the lambda sensors, as they have just been changed. is there some sensor that detects if the car is in motion or at a standstill while in drive that may be malfunctioning? the oil level in the gearbox is fine. i suspect the tickover is in fact high, and that in park or neutral it should sit at about 650-700 revs. however if set to that, the car stalls if in drive.

its as if there is some loading on the engine causing the rev level to drop?

john, im hoping you have the answer to this one?

Mike
 

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Mike

Well with the Soarer, i have just checked for you and it sits at about 700rpm when in P or N ,and when put into D it drops to about 600rpm which is normal as the torque converter is then engaged, wiating to drive ie the load on the engine is greater due to that so the revs will drop, but yours sitting at 1,000rpm seems high.


Andy
 

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Discussion Starter · #3 ·
i agree the tickover is high andy, tis the spread between drive and neutral revs that concerns me particularly. if i can find out why its happening, i can sort that and then drop the tickover overall.

Mike
 

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OK

Come on all you other auto owners out there let the guy know if yours is the same :).

Andy
 

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One explanation, and I am not a brainy car chic :D

the auto box puts a load on the engine when its in gear as soon as you come out of neutral, its why you have to keep your foot on the break. The load drops the engine revs, autos always have ahigher base idle because of this, however a drop from 1000 - 600rpm is excessive, it usually is 850-900 rpm base idle and will drop to 700 rpm
 

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Discussion Starter · #6 ·
hiyas kim,

yes thats the sort of spread im looking for, just got to find out why the car is needing such a high idle tickover in neutral to be able to achieve a reasonable tickover in drive.

i know about the loading etc. odd thing is, the car has had the engine changed. with the old engine, tickover spread was about what you have mentioned, however, since engine change i have had the problem i have already mentioned. this is why i ask, is there some sort of sensor on the car that may be faulty on the new engine, therefore causing this prob?

what does the crank idle sensor do? is it possible that if this is faulty?

I know that with some functions on the car, if an increase in loading is experienced, the car increases revs to accommodate. is it possible that this should also happen with the auto box, but something isnt telling the engine the right information?

Mike
 

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Mike.. firstly, Idle speed should be 650 +/- 50 rpm

When set to this, in P or N, I presume the engine runs fine, revs ok, and drops back to idle with no probs.. ?
Switch on the headlights, and other electrical items.. does the revs go down slightly, or does it stall? if it stalls, you may have a sticky or faulty BAC valve.
If it still runs ok, I think we can disregard the BAC valve.

Downside is there are only two other causes.

There is a connector on the end of the tranny (ten pins, 2x5) this is for the solenoid valves.. disconnect it, and put gear in D or 1 etc.
Does the problem still happen? if it seems OK, then you need to dismantle and clean the control valve body.
If it still stalls, the solenoid valve in the control valve body may be faulty, or worse, you may need to go to a scrappy, because you may have a faulty ECU..

So.. in brief:

set the idle to 650,
disconnect the solenoid connector,
give me the bad news.

John
 

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Discussion Starter · #8 ·
thanks john,

nice concise answer. ill follow the route you describe and let you know how i get on.

the car runs fine once you get going, but has the previously listed probs on tickover, its also running a bit rich i think, but that was before i changed the lambda sensors yesterday, so not sure of status at the moment re mixture etc.

ok, you know im not a tekki by any means, where is this control valve body and what does it look like? can i get to it from the top of the engine or is this an under the car job?

Mike
 

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Details will follow if necessary, but as you asked..

It's a large rectangular box, made up of metal sheets with small filters, and holes and slots in them, and is just inside the tranny, on the end, under the rectangular end cover.. the fluid has to be drained to remove it.

John
 

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Discussion Starter · #10 ·
john,

would this change in tickover and the resulting probs cause a fault in the valve body if the engine was changed?? the reason i ask is, there was no problem with tickover with the old engine, but was there from the outset with the new engine.

the engine came from a manual, but as i understand it, apart from drive plate changing etc, there is no difference in engines?

i can directly pinpoint the start of the prob to the new engine change, so am looking for pointers. perhaps on fitting the new engine sommat was connected up wrong? or not connected at all?

Mike
 

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The ECU receives signals from a variety of things..
for example, turn the steering wheel, and the revs should go up slightly...
put on the lights, and there is a slight change in revs..

basically, when there is a load placed on the engine, the ECU senses this, and then uses the BAC valve to control the idle speed.. i.e. give it a tad more juice.

So.. either you have a poor connection, or a non existant connection, or a faulty/sticking BAC valve.

set the idle speed, and turn on the lights, HRW, heater blower, A/C (if fitted) and turn the steering wheel.. if it stalls, its the BAC valve, if not, shift to D.. if it stalls, it is more likely the connection from the tranny to the ECU.

p.s

you never said it was after the engine change.. })

John
 

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Discussion Starter · #12 ·
john, sri about the delay, first chance i have had to try out the red 6. with all the lights on, if you turn the fans on full blast, the revs drop by about 250, dropping the tickover in neutral from 1000 to about 750. does this mean it could be the bac valve?

i dont suspect the box internals as they werent touched on the engine change and were fine before that.

if it is the bac valve, where is it? and what does it look like?

rgds

Mike
 

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The revs should stay the same... 650rpm when electrical load is on... and rise to 825rpm when A/C is on.

The valve is bolted under the throttle body..

There is actually two valves.. BAC (bypass air circuit) and ISC (idle speed circuit)
apparently, they can be dismantled and cleaned, but details are not in the manual.. it just says to replace if faulty.

Check electrical connections too.

John
 

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what does the crank idle sensor do? is it possible that if this is faulty?
Mike

Don't think your crank angle sensor would cause the problem - the job of the crank angle sensor is to generate signals to the ecu whink inturn generates signals for the Injectors and dissy telling the injectors when to open and the dissy when to fire.
This is done with the help of the front crank pulley which if you take a close look at it you will see it got 6 point all around it. As the pulley rotates the point passes the sensor thus the sensor sending info back to the ecu which then does it thing.

If you want to see pics of the pulley showing the points, let me know and I will post them.

William
 
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