Poor hot idle after a timing belt replacement

pcb

The Diagram Dude
:
2002 MP5
I'm guessing that maybe the ECU is holding the fuel trim at zero until it gets a handle on the idle?? (but I'm speculating)
 
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2003 Mazda protoge 5
Thanks, good to know, being that the ECM is holding the fuel trims until it has had a chance to learn is probably what it is.

HOWEVER, I just discovered the water pump just quit or so it looks like anyway. I have a hose coming for a leaky hose that goes to the throttle body as it was dripping and causing the recovery bottle to drop in level.

today, on the way home, the temperature climbed into the hot zone but when I got home (don't live far from work) after getting the hose ordered, I noticed the temperature issue and turned on the heat, it for the most part kept the temps out of the danger zone and when i got home and parked, the overflow bottle hadn't budged level from when I added some, I think yesterday, both cooling fans are working fine but a look-see under the car revealed the truth, it's dripping where the pump is, or on that side of the motor anyway so the radiator may be full but it may not be pumping coolant throughout the block so will have to see if borrowed wheels are possible for 2 days.

BTW, the belts are fine, the pump pulley is spinning.

Seems like if it's not one thing, it's another thing as the saga continues. :-(
 
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2002 Protege5
The water pump involves a lot of work to remove the belt covers and timing belt. Have you checked the thermostat opens when hot? If it is stuck closed the water temp will be very high. Weather will be near 80F all this week.
FWIW, on my motor the water pump would spin and was not leaking. The tines inside the motor had broken loose from the shaft and were not pushing any water. I found the issue with a scope down where the thermostat lives.
 
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2003 Mazda protoge 5
Per the pump, Oh I know all about the thermostat, in late summer of 2012, had the damn thing stuck shut and spewing coolant out of every orifice it could find, fortunately, I did the smart thing, turned on the heat and got it to Precision tune in University place and they checked it out thoroughly and the thermostat was the problem. Car had been fine until the radiator went in the fall of 2017 and they put in a new thermostat, along with lower hose as well and add to that, a very noticeable drip from that end of the motor to begin with.

Yeah, having replaced the timing belt, I know, not difficult, just a lot of crap to remove to get to it, including the timing belt and covers.
 
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protege5
check your radiator cap. Sometimes coolant problems can be simple cheap fixes.

IF the spring is weak (or missing, they can deteriorate) and it will fill the reservoir until it overflows as you drive. Once you park, it will suck the coolant back into the radiator so you never notice a leak. Once enough coolant is missing, it will run hot.

MAy not be your problem, but I always try and start with the simple things before diving deeper into more involved repairs. A lot of the time it saves a lot of time and money that way... Sometimes you get lucky. Sometimes not, but I'd rather go that route than replace the timing belt, water pump, thermostat, and a bunch of other stuff to find it doesn't fix the problem because the entire time it was something simple like the rad cap.
 
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2003 Mazda protoge 5
Problem is, and I say so in the post, it's dripping from the belt end of the motor, and the drops are not small either.

The cap, radiator and pump were all replaced by AAMCO 2 years ago.
 
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protege5
Problem is, and I say so in the post, it's dripping from the belt end of the motor, and the drops are not small either.

The cap, radiator and pump were all replaced by AAMCO 2 years ago.
Sorry, this post is like 700 pages long and I don't have the time to read the entire thing. Was just offering a suggestion :)

If you have drops coming from the belt side of the motor, it is probably the water pump. 2 years isn't a lot of time on a pump, but i've seen them fail sooner than that too. especially aftermarket pumps.
 
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2003 Mazda protoge 5
Pb4tugotobed,

sorry, I don't buy that excuse.

It's a discourtesy to skip over entries in a thread and then ask what's already been covered and say you don't have time. Obviously, you are here, so you are making time to read, right?

Anyway, back to the car, spent Friday and yesterday replacing the water pump and the small coolant hose to the throttle body and this time, make double sure that the timing was spot on and the car now idles smoothly down to 627 or so rpms, normal for this car, though I still get no short term fuel trims flirting between -3/+3 range and the car occasionally dies, but now I can put it in gear and it'll behave normally for the most part so the foot and dance is much improved. Now to just drive it and drove it to the store and it's more or less back its old self again, with the occasional stall notwithstanding. The fact that I can mostly now sit at the light with it in gear and it'll idle properly is a HUGE improvement over the past month+ of lumpy idle.

Now the relearn of the idle as I drive it. So far, never got a cat code so dodged a bullet there and the car seems to have a bit more pep to it than it did, not that it lost much but the throttle seems a tad snappier than it's been.

I did clear the codes and the low air flow code for the MAF came right back, but hope that goes away as the car relearns. The idle does fluctuate a touch, but not wavering wildly as it did between 1000-600rpm and often dies as it drops too low.

So now it's a wait and see how the car does.

then last night enjoyed a massive thunderstorm that blew through the area, knocking power out in many areas with multiple lightning strikes, heavy rain, hail etc, fun! Yes, my power did go out around 8:15pm as did many of my neighbors near me did as well.

Power was restored around 11pm to midnight time frame and awoke at 12:45pm to a blinking clock radio.

We don't usually get them this big and massive, but we sure did get a doozy last night though!
 
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protege5
Anyway, back to the car, spent Friday and yesterday replacing the water pump and the small coolant hose to the throttle body and this time, make double sure that the timing was spot on and the car now idles smoothly down to 627 or so rpms, normal for this car, though I still get no short term fuel trims flirting between -3/+3 range and the car
I still believe your timing was a tooth off on one of the cams. Enough to make it run bad but not enough that it wouldn't run. I've seen it happen more than once...

Pb4tugotobed,

sorry, I don't buy that excuse.

It's a discourtesy to skip over entries in a thread and then ask what's already been covered and say you don't have time. Obviously, you are here, so you are making time to read, right?
I'm not even going to comment on this... but good luck with the car.
 
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2003 Mazda protoge 5
As for the timing, I had hoped it would not be that as I had not been looking forward to tearing into that but you are likely right in the timing.

Thus the comment I made about double checking the timing when I put things back together after the water pump replacement. That whole reinstall went smoother than even I anticipated.
 
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protege5
As for the timing, I had hoped it would not be that as I had not been looking forward to tearing into that but you are likely right in the timing.

Thus the comment I made about double checking the timing when I put things back together after the water pump replacement. That whole reinstall went smoother than even I anticipated.
The first time always takes the most time. After you've done a timing belt or two (or two hundred...) it's not a big deal at all. Last timing belt I changed on my p5 only took me a couple hours start to finish, with beer breaks :)
 
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2003 Mazda protoge 5
Pcb,

Mostly, the dying is first few minutes of driving, once started up, after that it more or less drives like normal, so far and I think it just needs time to relearn so the jury is still out, at this point and time.

I have not gotten a cat code, nor does the car feel sluggish at all now.

So leaving home to work, or work to home, the first 3 minutes once rolling it will not always idle correctly but eventually does idle fine after a few minutes.
 

pcb

The Diagram Dude
:
2002 MP5
After start and during warmup, the ECU is supposed to control idle.

After a certain temperature threshold is reached the ECU hands off idle control to the IAC.

So if your initial idle is wonky then I don't know?

My car starts up, hits about 1200 RPM then slowly drops to idle speed of 720 RPMs.
The transition is smooth.
 
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2003 Mazda protoge 5
Once I get it to about 1200rpm and let it idle, the transition is smooth down to hot idle so that's fine, it's the initial start up, once it's been sitting and here, I just let it idle for about a couple of minutes or so before rolling and gradually, it'll run fine and like normal as the car is still re-learning is what I figure it's doing and I've not been driving it a lot in the past couple of days.

I'm thinking it's still too early to know if it's actually fine, the litmus test is does it improve as I drive it?

I have not run the scanner the past couple of days, but the low air flow code is apparently still present and add to that, the last I checked (which was over the weekend), the fuel trims have not budged and no misfires. Right now, it's back and fourth to work, which is less than 10 minutes each way for the most part.

One thing that may be different is now it's not guzzling down gas like it was, or so it seems but then again, I just put gas into it Monday evening after work and this weekend I'll get it on the highway and see how the car does, along with letting it idle.
 

pcb

The Diagram Dude
:
2002 MP5
If the outside temperature is relatively warm, then the ECU may try to hand over idle control very quickly. Perhaps that is what it is learning now and the idle will improve.
 
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2003 Mazda protoge 5
Good news,

Outside of needing to burp the cooling system, the car is back to its old self again.

It all was because of doing a grins and giggles try to see if any changes would commence by reinstalling the old MAF sensor and badda bing! STFT came back, MAF circuit low A code went away (had to clear that, but the live data said it's working), even my advanced time began to adjust for cyl. 1. So essentially, it's all good now.

May still need to finish re-learning but that's I think a simple procedure now.

Took some research, trying to see if the MAF sensor connector was bad and watching a whole lotta Scanner Danner (Paul Danner) on YT, many relating to the MAF, and a few others since last evening and even saw one Kia Sportage (an older one) stumble badly when the MAF dropped out and one car that was so beat down (2004 Infinity G57X I think it was) whereby the air filter was so bad it was disintegrating and had clogged up the MAF sensor and simply could not start.

Anyway, once burped, I should be good to go.

Oh, no odd noises anymore and the coolant does not appear to be leaking anymore too but air is in the system however - hence the overheating and/or lack of hot air out of the vents (tepid at best at times when not full on hot air).
 
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