I have a 99 ES with 50,000 miles on it.

Ever since I got it, it has had a problem of having an extremely lean mixture at idle. I believe all the 99-00 models having 1.8L engine have this situation. The lean mixture by itself is not a problem.

The problem is that at idle the engine almost stalls when the A/C engages and you happen to have your headlights on, brake lights on, and the radiator Fan is running. This is a typical situation on a summer night.

Due to the "almost stall" phenomenon, I can feel a jerk/jolt in the cabin as the engine recuperates due to the increase in idle speed signal sent out by the computer. But that signal is a feedback signal, not a proactive signal.

Is there any way the air flow mixture setting can be changed to be a little more rich at idle so as to be able to take the extra load?

 

i ahve had the same problem. even jsut as of yesterday my car stalled once with the AC on and the car jsut idling.
arul

 

hey arul,

u done some good work on ur car.

anyway, how to get rid of this problem?

 

Just outta curiousity, why are you so sure that the car is idling lean? There are all sorts of things that can cause the problems you're describing. How did you diagnose it?

 

Logic.

Do u have another reason?

 

About 6 months ago, my car had the exact same problem. I put the scanner on it and the coil packs were going bad. No problem ever since I changed them.

 

so you cahnaged the ignition coils
were those the ones in teh recall..
arul

 

That's basically what I was going to say. It's very unlikely that your idle is lean because OBDII cars have o2 sensors that actively correct the mixture. Try hooking the car up to an OBDII scanner and checking the fuel trim before you jump to conclusions.

Most engine problems on an OBDII car that aren't accompanied by a MIL are ignition-related. The ECU can sniff out most fuel-related problems, and the list of problems that will make the engine idle lean without throwing a code is VERY short. Also, your car DOES proactively correct for increased load when the a/c kicks on, the fact that it's chocking indicates that the engine isn't reacting the way it should.

I would check the following, roughly in order: plugs, plug wires, ignition coils [recall], injector spray pattern [TSB].

 

Day one May 1999: I purchased my Protege ES.
Day two, I noticed the jolt/jerk when A/C clutch engages, albeit erracically.
Between that day and now, I have been trying to hunt down the exact reason and I now have it.

The A/C jolt is only felt when the radiator fan kicks on, or if you have your rear defroster on and your headlights also running. Would be better if you had your foot on th brake(brake lights also draw power) and your gearshift is in either D,1,2,R

As regarding ignition coils, I had that changed 10,000 miles ago. Made no difference.

Logic:
Question: When does your engine stall?
Answer: When it does not have sufficient power to handle all the load that is dumped on it.

Expected Rebuttal: but the Computer does increase engine speed when it kicks on the A/C.

Answer: It does so, but is obviously slower than the speed with which the clutch engages.

The Fix: Either increase idle speed or increase the power at the same rpm.
increasing idle speeds has it own set of problems.
so the only recourse is to increase the richness of the mixture at idle speeds, thereby giving more power at the same rpm.


And this is the problem with the 1.8L engine. All owners of 1.8L engines have this problem. Ask Jstand6(jerry standefer). He will vouch for it. In fact he lost quite a few sales because customers felt the jerk while test driving the car.

And No. The 1.8L ES DOES NOT PROACTIVELY increase engine speed. if it did, this problem would not exist. It is sending out a signal for increase in speed, but the clutch engagement signal actually goes out first.

 

hey chikoo, i'm wondering, does this problem show up if you put the tranny in N when idling?

try that if you haven't done so.

EDIT: I'm a tard, just re-read your post, your problem only happens when it IS in neutral

but I doubt it's a fuel problem, more of an idling problem....

 

And why do you think richening will make power?
Unless you're way lean out of spec, richening won't improve power. People often associate richening with power for some reason, maybe due to increased detonation resistance, but thats not increasing power, in fact its decreasing it from what you would have if you didn't have to worry about detonation. People with turbo setups and bigger displacements / high CR etc richen it up as a safety net to make up for poor accuracy in fuel/spark tuning.

If detonation is not an issue, running leaner will (within reasonable bounds) actually increase power, as running rich takes up more cylinder space and reduces the amount of fuel burned, therefore reducing power (unless you're so lean as to not have enough fuel for the air).

But if you have an OBDII ECU, its going to be hard to do either.
Richening or leaning isn't really the solution, even if you could, as with such a small displacement motor more than likely any changes you could make would either be negative or insufficient...

 

Why are people obsessed with finding complicated solutions to simple problems??
All 1.8L ProtegeES made in 1999-2000 have this problem.

And believe it or not, it appears to me that Mazda could not fix this problem so they made it a 2.0L in 2001, so that it will have enough power at idle.




READ PROPERLY:
The A/C jolt is only felt when the radiator fan kicks on, or if you have your rear defroster on and your headlights also running. Would be better if you had your foot on th brake(brake lights also draw power) and your gearshift is in either D,1,2,R

NOT N or P.

 

So you're saying that in order to fix this problem you have, they decided to upgrade the ES trim level to 2 litres. No other reason ...

 

I am saying, one of the reasons. not the only reason.

 

I am purely speculating at this point.
Reason is:
The 1.8L was actually a debored 2.0L 626 engine.
The 626 does not have this problem.
Nor does the ES with 2.0L have this problem.
I can see a pattern here. If you don't better get yourself tested.


My conclusoin: It was a problem with their engg design of 1.8L.

btw,
I did own a 800cc car and never had the jerking problem. So it is only that suzuki did a better engg job than mazda.



Either I dont know english or you don't.
I said the problem occurs when in 1,2,D, or R, when the engine is under load. The more load you put on at idle, the more prominent the jerk/jolt.