FD idle / stalling problems

[CJay]

Some time ago, my 95 FD (PFC instaalled and mapped) developed an issue whereby it started to cut out when slowing down in traffic with the clucth in and the brake engaged. If I put the gearbox into neutral (manual) and cossted to a stop, I found that there was less of a chance of the engine stalling. Soon after, I found that the engine would cut out with 10 seconds of being started from hot or cold, starting again would usually be OK. Driving at motorway speeds is not a problem, in fact that engine runs really well @ speed.

Last night I removed the throttle body and reset the TPS values to 0.30 (VTA1) and 0.90 (VTA2) i.e. both values now in range (previusoly VTA2 was out of range @ 1.42) While I was at it, I removed the idle speed controller  valve from the rear of the plenum and gave it a good clean out with carb cleaner. I also lowered the idle speed down from 950rpm to 850rpm.

Unfortnately, this doesn\'t appear to have sorted the problem, in fact, its now worse. The engine still cuts out each time I start  (hot or cold) and its still stalling when coming to a stop.

One other thing worth mentioning is that the engine bucks when accellerating/decelerating @ anything lower than 2.5k rpm - I don\'t know if this is standard practice. I know that a faultly dashpot can cuase bucking on decel, as far as I can see the DP is operating correclty (I lubed it up with WD40 to be on the safe side).

I\'ve a bit of a quandry now in that I\'m unsure of the cause, it could be a faulty TPS or dashpot - I could replace them but still be in the same situation. I don\'t believe the ISC valve is at fault in terms of stalling when warm, although it could be responsible for cut outs when cold. The other possibility is that not enough fuel is being injected at idle and the map needs adjusting. As far as I can, I\'ve no boost leaks, all check valves look OK, the vacuum chamber is fine and all hoes are in good condition.

Is there anything I can check before I pull the rest of my hair out?!

CJ

[memski]

Clutch switch? Go to the sensor check screen and dip the clutch, if the clutch sensor doesn\'t light up then you know this is the problem.

[nikp]

You could try removing the idle valve plug. That way, you are taking the ECU out of the question: the idle is then managed mechanically by the two idle screws on the throttle body. Then report back with how it is then.

[CJay]

Clutch switch? Go to the sensor check screen and dip the clutch, if the clutch sensor doesn\'t light up then you know this is the problem.

Memski, any idea which one of these bad boys I should be looking at?



CJ

[CJay]

Clutch switch? Go to the sensor check screen and dip the clutch, if the clutch sensor doesn\'t light up then you know this is the problem.

Memski, any idea which one of these bad boys I should be looking at?

Edit - opened the sensor menu on the PFC and depressed the clutch @ idle - there was no change to any of the on/off indicators :2Rolleyes



CJ

[memski]

CLT, there should be a change when you depress the clutch. If no change then investigate the switch on the pedal, about 30 for a new one cured my problem :Thumbs-up

[CJay]

CLT, there should be a change when you depress the clutch. If no change then investigate the switch on the pedal, about 30 for a new one cured my problem :Thumbs-up

Thanks fella, the switch itself looks fine and is being depressed when the clucth is enaged, reckon a need to do a bit of rooting! On further investigation, it appears that wax rod on the fast idle cam is not extending when the water gets up to temp - looks like I\'ll need to replace that also :2Rolleyes

CJ

[Brett]

The wax pellets are a common failure on the older cars - got one going on my TII at the moment. (Exciting idle until its properly warmed up)

[CJay]

Firstly, memski - you\'re than man, thanks for the clutch switch tip :god

I checked continuity on the clutch switch with an ohmmeter, definetely fubared. Took it apart - the spring mechanism had snapped in half. Solution - opened up a push top pen, remove spring, fit spring in switch, fit switch back in place, test and hey presto, I\'ve got CLT on depressing the clutch  

The TPS VTA1 value on the commander started flashing while I was tricking about, I hadn\'t noticed this before. I started that, car, it cut right out. I depressed the acc pedal and the VTA1 voltage reading stopped flashing, started it up and the engine idled fine. I then pushed on the plug connected to the TPS and the car cut out straight away. So, it looks like the TPS (or the TPS wiring) is fubared as well.

While I\'m at it, heres a pic of the plunger that engages the fast idle cam, the engine is fully heated (water temp c. 75 deg) - should it be extending more than it currently is?



CJ

[memski]

No worries, good to hear you\'re making some progress.

[ianelvar]

While I\'m at it, heres a pic of the plunger that engages the fast idle cam, the engine is fully heated (water temp c. 75 deg) - should it be extending more than it currently is?



CJ

Doesn\'t look too bad. I\'ve just been through this myself.

http://www.mazdarotaryclub.com/forums/showthread.php?t=40062

Just make sure that when it\'s extended the cam moves right off the follower. you can do this by pushing that arm with the screw with the spring around it down away from the wax rod, and looking at the throttle linkage. If it moves, then it\'s not disengaging properly. You\'ve got plenty of travel left on that screw, so just wind it in a little until the fast idle cam is fully disengaged.
You may then need to reset your idle, and possibly the TPS.

[CJay]

Thanks for the tip ianelvar, I\'ve marked the plunger with a pencil and will check it later to see if it extends out. I\'ll also give the bleeding a go - worth a try!

When I push on the fast idle cam screw, the unit doesn\'t lock into place as per your video in the other thread, it moves freely back and forth. What do you reckon, new fast idle cam required?

CJ

[ianelvar]

No, sounds yours is actually in great shape! I meant to explain that in my post, but forgot. Its not supposed to lock - mine only does so because the little roller on the follower is jammed tight.
Glad you found it helpful though.

[BenLewisMav]

I take it you sorted it out?
Just a thought but did you try bleeding the clutch cylinders and adjusting the clutch pedal? Sounds symptomatic of a dragging (not disengaging properly) clutch, esp. the bit about being in neutral reducing the chance of stalling

[CJay]

I take it you sorted it out?
Just a thought but did you try bleeding the clutch cylinders and adjusting the clutch pedal? Sounds symptomatic of a dragging (not disengaging properly) clutch, esp. the bit about being in neutral reducing the chance of stalling

Nice tip about the clutch cylinders Ben, I\'ll keep it in mind. I sorted the issue by replacing the TPS, it idles pretty well now without any stalling etc.

CJ