Poor hot idle after a timing belt replacement

pcb

The Diagram Dude
:
2002 MP5
Does your code reader give you the actual code number or just an explanation?

There are three codes our car has for the MAF.

A broken wire. A shorted wire. Or wonky numbers.

 

pcb

The Diagram Dude
:
2002 MP5
Oh, and unfortunately, driving around with your CEL flashing can fry your pre-cat.

An engine misfire is the only code that flashes the CEL, then the ECU goes into limp mode and tries to stop the misfiring.
Once the ECU stops the misfiring, the cel goes solid.

Keep your eyes open for a P0421code for a burnt pre-cat.

Raw gas on the pre-cat burns it out but you can get a misfire due to no or little fuel which is safer for your pre-cat.
 
:
2003 Mazda protoge 5
I've heard of that, yes, also water too or water and soap. Tried the water in a spray bottle and so far have not found any leaks when I last did it a week or so ago.
 
:
2003 Mazda protoge 5
As to the flashing CEL, it only did it for a bit then went back to solid red by the next day and has stayed that way since.
 

pcb

The Diagram Dude
:
2002 MP5
I remember disconnecting my battery then drove through town with multiple stops and idles and my car was fine, then I got on the highway for 1/2 hr, got into the next city and it idled like shit and nearly stalled a few times.

The ECU needs to learn how to idle the car at different temperatures and conditions, that's why it takes so long.

But if your battery wasn't disconnected then that shouldn't be happening.

Thinking about it (and speculating), If the ECU thinks there is less air going into the engine then it would probably give less fuel which could cause a misfire.

You may have a bad MAF or a broken/shorted wire.
 

pcb

The Diagram Dude
:
2002 MP5
I've heard of that, yes, also water too or water and soap. Tried the water in a spray bottle and so far have not found any leaks when I last did it a week or so ago.
Carb cleaner works great.
You just spray it around your engine and all vacuum lines and such, then when the RPMs increase, you've found the leak.

It's way easier to find a small or hidden leak.
 

pcb

The Diagram Dude
:
2002 MP5
P0102, MAF low
P0103 MAF voltage circuit too high
P0230 Camshaft sensor (mine has scratches on the surface, bad?)
P0300 (obviously as it's the general random misfire)
P0304 Cylinder 4 misfire
P0401 EGR flow insufficient
Just noticed this.
If your MAF is giving both high and low voltage, without a bad data code then I would suspect a faulty MAF.

I would suspect that if you had an intermittent vacuum leak big enough to throw both codes you would hear it.

If it were me, I'd trust the codes and get a new MAF. (maybe after a carb cleaner vacuum test)

They're about $55 US.

 
:
2003 Mazda protoge 5
Actually, the P0102 is for low air flow, not voltage. The reading the scanner gave me is 7Lb/s I believe it was so above the 217g/s max. It needs to be above 0g/s and 217g/s so that is the issue?

Anyway, went to find a JIS bit for removing the IAC valve to ensure it's clean and had to Google what JIS was, unfortunately, no one actually makes a true JIS driver or bit, though some make a combo JIS/Phillips that hold onto the bit very well so no camming out once torqued (thus stripping out the head) and is a compromise in any case, not even Vessel makes the true JIS anymore. I bought some bits that might be an improvement over what I have already to see if it bites into the screws properly aren't much.

Glad other places like Rock Auto sells the MAF for way better than what Parts Warehouse sells them for. The Delphi model was quoted as being $400. Found some on Amazon that were as low as 26.75 or some such a price, way better.

Anyway, took the car for a quick drive, though goofed and didn't get as long a drive in as I had intended, but the car seems to be idling a bit better? After getting off the freeway and heading ups some steep hills here in town, the idle was much smoother, though not perfect (these cars as you may well know, are not the smoothest motors when at idle, but not agricultural like an Iron Duke 4 though!). It's still misfiring, but nothing like it was and the same 3 codes that come up as generic P codes, P0102, P0103, and P0300 so far after the run. Still comes up evap incomplete and a couple of other parameters are also incomplete. Car ran smooth and was quite responsive however and ecceleration was smooth with no hesitation due to recovering from a bad misfire and so far no pre-cat codes showing, not anything else pending at this time.
 

pcb

The Diagram Dude
:
2002 MP5
Actually, the P0102 is for low air flow, not voltage. The reading the scanner gave me is 7Lb/s I believe it was so above the 217g/s max. It needs to be above 0g/s and 217g/s so that is the issue?
I don't know how many grams it needs.

 

pcb

The Diagram Dude
:
2002 MP5
I think you've got a bad MAF and replacing it may very well clear all your codes and quite possibly stop the misfiring.

The ECU isn't getting proper MAF data so it's just guessing and quite possibly causing the misfire.

Check your wires and connectors going to the MAF for breaks, shorts or corrosion.
 
:
2003 Mazda protoge 5
Quite possibly and going with either Amazon or Rock Auto will yield one at a decent to quite affordable price point, rather than upwards of $400 for a Delphi unit locally.
 

pcb

The Diagram Dude
:
2002 MP5
Amazon might be a better bet.

I've been waiting three weeks now for my damn axle nuts from RockAuto.
They were supposed to be here by Aug. 13th.

Amazon sounds cheaper but make sure it's the right part and not a piece of crap.
 
:
2003 Mazda protoge 5
Yeah, that has indeed crossed my mind, especially for the coils as I can get TWO of those buggers for the price of just one at Rock Auto (around 23 dollar and change) for one at Rock Auto, the same price for both via Amazon.

heck, even the Delphi units sold at Rock were MUCH cheaper than the price I was quoted at Parts Warehouse not far from my home ($400 was the price) so definitely won't break the bank and actually can be quite affordable, depending on what you get.
 

pcb

The Diagram Dude
:
2002 MP5
I've been waiting three weeks now for my damn axle nuts from RockAuto.
In fairness, I did go with the cheapest shipping option and RockAuto is a very well organized website.

You are way more inclined to get the right parts.

PS. Coils for our car can be a real source of problems. They can be bad right out of the box and fail intermittently and can be hard to diagnose.

It's the only part I might go with OEM or at least get the Hitachi version.

If you get your codes cleared with a new MAF but the misfire returns start with new quality coils.
 
:
protege5
I didn't read real carefully, but here's my take.

Clean the MAF. You can get a can of MAF cleaner or just use carb cleaner. If they're dirty (and frequently are) cleaning the dirt off the element can help that. If cleaning it helps, keep running it and replace it if the MIL returns with a MAF code after a while. Cleaning is a good diagnostic aid, however for dirty maf problems. IF you had a better scan tool that shows live data there's other tests that help to narrow down a MAF issue but it doesn't sound like your reader is capable.

I would also recommend double checking the timing marks. Did you roll the engine over by hand after you released the tensioner? These motors are kind of a pain in the ass to set the timing belt up. It usually took me a couple tries before I rolled it over by hand and had all 3 timing marks line up correctly after rotating the engine over a couple revolutions. If they're not dead on, it will still run, though will have some misfire issues because valve timing is a little off, and it won't run quite "right".

While possible, I find it unlikely that the ignition coils failed at the exact same time as the timing belt. quite the coincidence...

I would also do a compression test to make sure nothing did hit. These are listed as an interference engine by Mazda. I've had 2 timing belts break on my car over and no damage or issues, but it's possible still. Even with over 260,000 miles mine had between 200-210psi on all 4 cylinders when I sold it. If you have a cylinder that's low it's not going to idle right. Also as said, if battery is disconnected or low enough to reset your radio presets it may have reset the engine computer and take a while to relearn the idle.

Also, carefully check to make sure you hooked your grounds back up near the motor mounts. funny things can happen when grounds are left loose...
 
:
2003 Mazda protoge 5
First off, this motor appears to be NON interference and has never been rebuilt and I didn't hear anything hit anything, just it stopped running and the dash lights came on. Starts fine, sounds normal and a simple blip of the key get is going once warmed up acceleration is really good for 188K+ miles.

Secondly, I did spray out the MAF, no change, only the P0102/103 for the MAF sensor and the P0300 codes remain. I had cleared out the codes, but the P0102/103 and the P0300 came right back, the rest, the P0340, cam shaft sensor, P0304, cyl 4 misfire and the P0401, EGR have not returned.

So it's looking like the MAF is out of spec and perhaps confusing the ECM. So I'll get one ordered up tonight and hopefully we'll get it in a day or two and we'll find out!
 
:
2003 Mazda protoge 5
A brief update;

I should have the MAF sensor ordered by now if not at some point today via Amazon because I have access to Prime (via a friend) so we can get it within a couple of days most likely as time is of the essence due to hoping to avoid having a damaged cat.

So far, I've not run into the P0420, catalytic converter fault code but the O2 sensors show good on my Launch, but I still have the Evap and cat tests as incomplete for the inspection and maintenance testing mode of the scanner.

I did buy a new gas cap since they don't cost much and a likely and cheap insurance for a possible evap leak yesterday. Still have the MAF and the P0300 codes for faulty MAF sensor and random misfires.

Hopefully by the weekend to have this resolved. Stay tuned.
 
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