GX 470 2008 Stalls randomly in traffic.
- Thread starter DFuller
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
For something like this you'll need to livestream sensor data to figure it out. I've had that problem a few times in my rig and it was the wiring to the MAF sensor, I only figured it out due to running Torque Pro and having a live plot of MAF data vs. time. The MAF would randomly under-report air due to the wiring issues, which would then cause the computer to cut fuel and kill the engine. No codes. I'd plot MAF sensor data, commanded air-fuel data, and actual air-fuel data. Then you can see if the MAF is acting funny or if it is something else causing it to randomly go lean. Or, if you have an ignition/electrical issue causing the problem.
I agree with Rednexus above. I had a stalling issue that was due to a dirty gummed up throttle body and MAF. You can buy a $15 kit at Walmart that includes spray for MAF and throttle body. Only use MAF cleaner on the MAF! These are very sensitive. Use an old tooth brush for the throttle body. You need to do a throttle relearn procedure once cleaned. Completely fixed my problem
- Thread starter
- #4
I cleaned the throttle body last night. Did it last summer as well. Was not terrible. I also cleaned the Mass Airflow Sensor. I have a Hewitt SAIS bypass installed but I’ve had that for a few yrs now.
I noticed today some bronze/brass shavings around the ID on my PS drive pulley. Both inside and out like a brass bushing is wearing out. Steering is a little noisy and hard I noticed today. Maybe locking up and stalling???
How often are you getting the stalling? I think that a failing PS pulley would eventually cause the serpentine belt to fail, but not stall the engine. I'd still get live data like @Rednexus suggested.
Reach out to Hewitt about this. I had the same, and it turns out for a few years they had intermittent issues with wiring harnesses. Have you noticed whether this primarily happens when the car is cold started?
Originally i thought mine was a transmission issue. Cleaned the maf. Repalced the maf. Cleaned the throttle body. Cleaned sparks. Replaced air filter. Only thing that fixed it was replacing the SAIS system with OEM parts.
Originally i thought mine was a transmission issue. Cleaned the maf. Repalced the maf. Cleaned the throttle body. Cleaned sparks. Replaced air filter. Only thing that fixed it was replacing the SAIS system with OEM parts.
- Thread starter
- #7
I reached out to Paul today. He suggested I unplug it and return to stock. I have the block off plates installed so not sure about that.
It is not at cold starts, after being driven and warmed up primarily. It’s always re-started with no issues. It’s always been very reliable so it’s odd.
- Thread starter
- #8
Did you do the work yourself restoring the original SAIS?
Have you checked the MAF readings while the engine is running? Otherwise, it's premature to think about replacing SAIS parts. A number of us have had similar problems on here due to a bad MAF connector, which is $16 on Amazon. Without checking the connection, you run the risk of replacing parts that aren't bad and having the same problems.
I checked the MAF readings on mine, and have had the new SAIS kit with no stalls for a year on mine- not sure if you were asking me or him. Agreed- def check MAF numbers first
- Thread starter
- #11
I need to check those readings. Thx for the advice.
Hi, have you fixed this problem yet? May have the exact same problem. It randomly dies and always restarts. Mine also have the Hewitt bypass installed. Would appreciate for more info! Best,
Plot the MAF readings vs. time using TorquePro or a handheld scanner that can give you graphs of live data/sensor readings vs. time. You should have a smooth plot. If you are getting abnormal blips in your MAF readings that correspond with a stalling/hesitation/surging issue, the issue is likely the MAF or the MAF connector.
Per my previous posts, the MAF connectors on these rigs are fragile; something as innocuous as unplugging the MAF connector to plug in a Hewitt SAIS bypass may be enough to damage the connector and cause all sorts of strange behavior (that will sometimes, but not always, throw a code). Many of us on here have had MAF connector issues, so it's very common, and will become more common the older these rigs get.
Cool! Thank you for the reply! Yeah, when the car is idling, I find that it keeps wanting to rav to above 2000rpm. I will definitely look into that.
This sounds more like a MAF issue to me. I dont understand the technical details of them failure mode of the SAIS bypass kit, but mine seemed to stall out of the bottom end of the rev range after starting the car, driving for a few minutes, then coming to a stop and idling in drive.
After trying really hard to keep data and isolate variables, all i could really tell was that it tended to stall if i pulled up to a light or took a sub-90° corner (engine dropping to idle while in drive) around the 5-10 minute mark after starting the car.
There are reports on the first gen 4.7L Tundra forum of the SAIS bypass kits going bad. Try uninstalling the kit from the MAF and see if you continue having the same problem.
Additionally, I had a similar problem with my first gen Tundra 4.7L where it would warm up with some throttle surging and then die at the first stop sign at the end of my street. It would then immediately restart without issue and operate fine. This problem was fixed by cleaning the throttle body flapper which was gummed up with oily residue and also cleaning the MAF. Might be worth a try.
Additionally, I had a similar problem with my first gen Tundra 4.7L where it would warm up with some throttle surging and then die at the first stop sign at the end of my street. It would then immediately restart without issue and operate fine. This problem was fixed by cleaning the throttle body flapper which was gummed up with oily residue and also cleaning the MAF. Might be worth a try.