Surging throttle

[KingKona]

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[TW Merema]

Soooo, I’m dumping my dealer. CEL popped up again Sunday night, I read the code as noted above. Took it in yesterday, they tell me there are NO codes stored. I showed them the pictures of the codes I read. Nope, none stored. On my way home, CEL popped again, I get the codes, the same 2 are in there. To be fair, the air shutter code isn’t throwing a light, but come on guys…hoping the next dealer is not incompetent.

 

[TW Merema]

Oh and before anyone asks I am NOT clearing the codes when I read them.

 

[TW Merema]

Interesting news, light popped up again today so I took to the dealer as they asked me to. COuldn't possibly pull the codes, no time today. Come back Monday lol. Eff this dealer, came home and jumped on the oscilloscope feature of Forscan. Logged the sensors, and sure enough bank 1 shows faults. When the fault happens it also causes something weird to show up in the throttle body position too, so my guess is this is causing the surges. They happen exactly when the faults occur so I've correlated it to this issue. I swapped the sensors, and the fault did not follow the sensor so it's the wiring or the PCM. Now to get the dealer asshats to actually take a look, thats another issue altogether. I'll let y'all know how it turns out. Here is a pic of the log in case anyone wants to see it.

 

[Cobra Jet]

Well, I got some more information on the issue I believe. Last night on the highway about 2000 rpm in 6th gear (cruise set) I got a CEL. Pulled the code and got a P0369 Cam Position Sensor B Circuit Intermittent (Bank 1). Both cam sensors seem to be plugged in properly and don't look suspect, but I'm going back to the dealer with new info. I'll update if I get an answer.

Plugged in properly and operating properly are 2 different things. I think on the GT350’s there’s a known issue that the cam sensor harnesses get damaged due to being too short and cause sporadic issues.

Check your harnesses to the cam sensors - not just by looking at them, but pull the connectors and do continuity tests on the connector pins AND do the same with the actual sensors. Compare your readings of sensors to what they should be for a good sensor.

Any sensor or connector can look good, but that’s not to say there’s an issue within the wiring casing, connector pins or sensor itself.

Also check the crank sensor too. There have been M6G members that found the crank sensor to be faulty AND/OR the pins within the connector to be loose, which causes weird faults too.

If you’re getting AGS errors or issues, again try and check the harnesses/connectors for continuity. Make sure the harness to the AGS motor isn’t loose.

Check all ground points within the engine bay too.

Look under the car and make sure any harnesses around the engine/trans/front end are not pinched or chafed, causing a short.

 

[TW Merema]

Plugged in properly and operating properly are 2 different things. I think on the GT350’s there’s a known issue that the cam sensor harnesses get damaged due to being too short and cause sporadic issues.

Check your harnesses to the cam sensors - not just by looking at them, but pull the connectors and do continuity tests on the connector pins AND do the same with the actual sensors. Compare your readings of sensors to what they should be for a good sensor.

Any sensor or connector can look good, but that’s not to say there’s an issue within the wiring casing, connector pins or sensor itself.

Also check the crank sensor too. There have been M6G members that found the crank sensor to be faulty AND/OR the pins within the connector to be loose, which causes weird faults too.

If you’re getting AGS errors or issues, again try and check the harnesses/connectors for continuity. Make sure the harness to the AGS motor isn’t loose.

Check all ground points within the engine bay too.

Look under the car and make sure any harnesses around the engine/trans/front end are not pinched or chafed, causing a short.

I’ll definitely check into the harnesses. I did a quick and dirty test just now, swapped the sensors from exhaust to intake side and the fault stayed with the exhaust side so that means it’s got to be wiring (or possibly a cam relcut or wheel/timing issue?). What’s odd is that these faults WILL NOT trigger while the car is at idle, only while driving. I unplugged a cam sensor while idling and immediately got a rough idle and DTC. Idk I hate to mess with it too much since it’s under warranty, and I definitely don’t want to track down a harness issue. I just like to have all my info straight when I go to the dealer service department and show them where the problem is, they only have to fix it.

 

[Mspider]

Understand and appreciate that, but to the root of the issue why would a catback exhaust cause this problem on this particular Mustang when it seems none of the other 8 million Mustangs with catbacks have the issue?

Dealerships have gotten a lot worse in recent times with aftermarket parts. And they can blame anything on anything. I think most people who own mustangs leave them mostly stock anyways.

 

[TW Merema]

Just figured I’d update in case anyone reads this years down the road. I finally got the dealer to read the codes and actually diagnose the issue. They are replacing VCT solenoids so let’s hope that helps. I pick it up tomorrow so we shall see…

 

[TW Merema]

The saga continues…VCT solenoid didn’t help (as I suspected, but they have procedures). Check engine light came back on next day while the surging during part throttle cruise continues. The tech actually called me, and we discussed everything they have done to diagnose, and he asked what I had noticed. He was actually very interested in the logs I’d taken, and had me send them. Asked if it was tuned, I had to answer with “I don’t know” since I just bought the car a month ago. We decided going back to the factory tune might be a good step, so he reflashed the PCM to factory. He also mentioned an SSM bulletin that said cars built in this date range with code P0369 were to receive a new bank 1 cylinder head. Something about a “Mega cap” that’s out of spec…don’t know what a mega cap is but he ordered the head. To be installed once it comes in, let’s hope and pray this solves it, because if it doesn’t I’m driving it off a cliff.

 

[2022 Mach 1]

No Ford Pass available which record the CEL date and time on the 2020?

I pulled my 5 day old Mach 1 in with 87 miles and they told me there are no codes.

I pulled out the message I got on my ford pass. All of a sudden I'm getting a new spark plug.

 

[TW Merema]

Originally I showed them that, plus the actual P-codes that I viewed with Forscan, and eventually showed them the fault logs that showed the sensor itself detecting the fault. At first they tried to tell me if the light isn’t on they can’t get codes, but I know that’s nonsense. Customer service aint what it used to be…

 

[TW Merema]

Cylinder head and gaskets have arrived at the dealer. Appointment in a week to have the work done. May the odds be ever in my favor…

 

[Ock]

You need to call Ford and open an escalation ticket. They will ensure dealers does due diligence. I had too, took 4 months but my issues were all fixed. You will need to keep on Ford and dealer but if its under warranty and the cant 100% prove that any after market parts are causing it they have to fix it. Just dont give up, its a pain...but worth it.

 

[SnakeMaster16]

I experienced a somewhat similar issue when I bought my car (used @3k miles). The engine had a constant surging pattern at steady throttle, in any gear, cruise control on or off. My vacuum gauge showed further movement than yours, and I could actually hear the engine trying to load up in the exhaust note. It was like a 2-second cycle, load up and unload, constantly.

I never got any DTCs, however. My dealership replaced the electronic throttle body and intake cam phasers, neither of which fixed the problem. They eventually had a Ford engineer take a look, who approved an engine replacement, which solved the problem. I never got any word on what the cause of the problem was, if they ever found it.

I haven't had any problems in 30k miles since!

I hope in your case it's just a simple sensor or something. I haven't really seen anyone else with a similar problem to mine, I'll be following this thread for sure.

Crap, this sounds like what my car does. No codes or anything wrong otherwise. I just always noticed that constant pattern at cruising speed. The only question I have is I'm not sure it if it was present at stock or after I installed the Ford Performance intake, TB and calibration. Which of course would make me scared to take it in like yours cause they will blame it on the mod and I'm not paying for a new engine. I will check the vacuum gauge while driving to see how much movement, but the way you described it definitely sounds like what I hear while cruising. Any advice?

 

[TW Merema]

Crap, this sounds like what my car does. No codes or anything wrong otherwise. I just always noticed that constant pattern at cruising speed. The only question I have is I'm not sure it if it was present at stock or after I installed the Ford Performance intake, TB and calibration. Which of course would make me scared to take it in like yours cause they will blame it on the mod and I'm not paying for a new engine. I will check the vacuum gauge while driving to see how much movement, but the way you described it definitely sounds like what I hear while cruising. Any advice?

If the car is under warranty take it in. This issue stems from a defect in the head itself, none of which would be attributable to the air intake changes you made. It does apply to a narrow range of build dates, 9/1/2020-12/1/2020 if memory serves. Look at your drivers valve cover sticker for your engine build date.

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