When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A few months ago, I bought a 2011 that wouldnt start i have a post dedicated to it, so I’lll spare the backstory other than to say PO told me car simply shut off one day getting on interstate and would only run by using a lot of throttle.i replaced ignition components and have gotten car to run twice then floods.
The throttle body has been apart as the sensor is held to the TB by a single piece of thick aluminum wire. Pushing on TB plate directly, I can hear the gearing inside turn as plate is moved.
With key on, and using throttle….I dont hear plate move until pedal is depressed around 50%. I do not have a CEL for this, but I would like to assume the throttle plate would move in proportion to throttle input instead of what I am noticing.
If it's been apart who knows what has been messed with. Perhaps the throttle motor wasn't indexed properly when reinstalling. No way to tell from here on the internet but suggest you start with a known good throttle body from the same year.
When you first key on the ignition or when you key off, does the throttle do a complete movement properly? It's supposed to self-test.
Do you know the engine compression? Before spending more effort that might be important.
Good to know on the self test. I do not hear it move when the key is turned on, but I will get a helper to turn the key on while I listen under hood. I was able to start car the other day and kept it running with throttle. Car warmed up and finally burned off the fuel, managed to get it to idle around 1200-1500 rpm with foot on throttle. Tried to slowly back out once at normal temp and it stumbled, died and flooded again. That’s when I heard the tb movement not coincidental with throttlw.
when car died on PO, it was brought to Mazda. They did a compression test (one chamber low but still in spec), deflooded and suggested new ignition components. PO replaced coils and plugs then drove it before dying while getting on interstate. PO said car died like a switch was turned off…so I keep looking to electrical components as a source.
Appreciate the reply!
Last edited by Bayou_Flyer; 12-27-2021 at 10:57 AM.
Fuel pump maybe. If it shut off like that and only runs with pedal pressed maybe the pump can't maintain a constant pressure. Just a thought. Good luck.
Perhaps...the fuel gauge is stuck around the halfway point (which I “think” means the sensor issue is on the pump assembly...but admit still learning about that). The pump access panel has been off before...but I know pump has not been changed (132k miles).
I deflooded the car and got it to run yesterday for about 15 min. Got it up to normal temp using the throttle. It did it’s fair share of popping/smoking/backfiring until the fuel was all burned off. I slowly backed off the throttle and had it idling 900-1000 rpm. As soon as I let off the last bit of throttle...it died.
Last edited by Bayou_Flyer; 12-29-2021 at 09:30 AM.
It's not unusual for it to need to learn to idle, especially if things aren't exactly in factory spec.
Do you have a way to read your fuel trims? Could be as simple as a vacuum leak (especially if the throttle has been apart before). Since you're able to control it, I'd say the throttle body movement thing is a bit of a red herring.
Yes, it very well could be. Just for more info…when I turn key on, I dont hear TB move. If I push pedal to floor and turn key on…I hear the TB move. Wondering if it possible that whoever disassembled the TB, reassembled it incorrectly?
i dont have the ability to read the fuel trim, and I had hopes that it running for so long wouldve given me some benefit.
Because the TB is so janky, I’ll just pick up another. Found one with under 100k miles of use for $50. It came from a running car, so hope to at least rule it out and move on.
Last edited by Bayou_Flyer; 12-29-2021 at 04:53 PM.
Front o2 sensor could be faulty. Stopping it from learning trims. I had that problem but it would idle until it tried to start using the o2. (Closed loop I think).
Good to know. I remembered the PO saying something about the O2 sensor….I was thinking of the one in the cat. With over 100k over n the clock, and no record of those ever being changed, I’ll add it to the “it needs to be done anyway” list. Thanks!
Trims are not going to keep it from idling, it may fluctuate etc. because of trims, but not die.
Did you ever put a different TB on yet? Because that last ‘bit of pedal lift and then it died’ screams bad TB. That’s where the idle control is, and obviously it’s not being controlled.
Trims are not going to keep it from idling, it may fluctuate etc. because of trims, but not die.
Did you ever put a different TB on yet? Because that last ‘bit of pedal lift and then it died’ screams bad TB. That’s where the idle control is, and obviously it’s not being controlled.
So at the time this o2 problem was happening. I just had the engine rebuilt. Meaning the batt has been out of the car for a long time. When we put the engine in and got it started the fuel trims. Ltft and stft were both 0 and never changed. So when the car gets started it runs enough to warm the o2 sensor (closed loop). Means the ecu is controling fuel. Once warm it start relying on the o2 sensor to give feed back and adjust trims to keep it running. Well there are no trims. Once that change to open loop the sensor is bad and doesn't know what to do and it dies. I put an o2 sensor in and problem was fixed. I see trims changing and learning and the car doesn't stall.
Trims are not going to keep it from idling, it may fluctuate etc. because of trims, but not die.
Did you ever put a different TB on yet? Because that last ‘bit of pedal lift and then it died’ screams bad TB. That’s where the idle control is, and obviously it’s not being controlled.
I have a TB coming from LQK...will update once in. I remember my previous S2 throttle body self testing when the key was turned on, and that this one ONLY does that if the pedal is on the floor at least makes me think whoever disassembled it had good intentions but a bad result.
What the heck, was there a small fire in there? Is that oil on the filter? Is there oil elsewhere in the intake tract? This can happen due to excessive blowby pushing oil into the intake.. but I can't fathom how the funnel would have been melted like that.
No oil on it….no oil in the tube. Have no idea what/when happened. Unless the PO had put some fuel down the intake? Anyway, the front side
of the MAF is also scorched around the bottom edges. Crazy!
Regarding the TB…I noted the one on the car was easy yo open by pushing on the plate. The one I bought is very tight, but I did not force it to open. Is that proper to be tougher to open? Good thing about LQK is that it can be sent back if it is seized.
Thanks. I plan to disassemble the TB to see if anything appears amiss. With the plastic cover removed, the gears turned as the plate moved. When it was on the car, I didnt hear any movement until the pedal was about 50% depressed. Makes me also wonder if there could be anything in the pedal assembly that would cause that? Baby steps…
I would see how it behaves with the new throttle. It's drive by wire so if the engine is off and there's no airflow measurements, not opening might be the correct programming. My car is sleeping for the winter, otherwise I'd go out and see what it does in the same situation. Maybe someone else can confirm?
That is good to know….I now recall reading about the force being enough to lob off fingers. Not sure if true, but the fact that the old TB was easy to move makes me feel getting the newer one was a good move.
Battery installed, car deflooded, got it to run but wont idle without using throttle. Pops and backfires too. After engine warned up, I through it into drive and was able to drive it around. Didnt want to move happily but once going it took off and ran better. I drove it around the parking lot for about 10 minutes until it started to stumble. CEL came on for P0171 “system too lean”…Guess could be the burned MAF, bad front O2 (which I have in a box), or vac leaks.
Yeah I'd say burning the MAF might have something to do with it. See if it runs better with the MAF unplugged?
If it's showing lean, the MAF is reading low or air is getting in somewhere else. Maybe have a look at what airflow g/sec it shows while maintaining 800rpm idle (or light feathering) while warmed up.
Yeah I'd say burning the MAF might have something to do with it. See if it runs better with the MAF unplugged?
If it's showing lean, the MAF is reading low or air is getting in somewhere else. Maybe have a look at what airflow g/sec it shows while maintaining 800rpm idle (or light feathering) while warmed up.
Got it deflooded, unplugged MAF, fired up and stabilized at 2000rpm for a bit then started lowering to 750-800. Then died after a few minutes at idle. However, that def tells me the MAF is one of the issues.
12-27-2021, 08:55 AM
