Stock ECU not richening under boost

[4CylinderSpecial]

So I have a weird condition happening. Went to switch back to my stock Gen 3 ECU from the Power FC. Went onto the motorway on-ramp in 2nd and floored it. The engine feels like it's stumbling or missing and is generally sluggish. WTF... Shift to 3rd and keep going, engine bucks and I let off. Kept an eye and let the car hit around 4 psi and noticed that my afrs are not dropping at all. Seemed to be that the ECU isn't seeing boost or anything at all. Sometimes it will drop to 10 or 11:1 but then climb back up and cut. This isn't an overboost as I set boost controller to 14lbs. Checked FPR hoses and MAP lines.

Last resort is that I switched back in the Power FC and everything is fine. You can check sensor operation in the PFC and everything works and shows up as working. Car richens under boost properly with this ecu and no problems at all. Spark plugs look fine and are gapped properly.

Anyone had an issue with the ECU like this before? Had a quick look at the caps and couldn't see anything wrong. Initially thought fuel pump/pressure but an ECU change shouldn't have solved that.

[Benckj]

Are you using any sensors that are not OEM?
I know with my EMS an IAT was installed and calibrated to replace the crap Toyota one.

Another thought is the timing is generally adjusted to base value when setting up EMS along with a MAP if included.

[4CylinderSpecial]

Are you using any sensors that are not OEM?
I know with my EMS an IAT was installed and calibrated to replace the crap Toyota one.

Another thought is the timing is generally adjusted to base value when setting up EMS along with a MAP if included.

All my sensors are still stock as the power fc is capable of using them all so no worries there.

Map sensor is stock and timing is at 10 deg idle when locking the idle control. Wondering if this is the stock ecu slowly dying?

[Benckj]

I wouldn’t think it was the ECU dying. Normally when ECU dies you get strange idle or ignition missing not internal fuel map issues.

[4CylinderSpecial]

I wouldn’t think it was the ECU dying. Normally when ECU dies you get strange idle or ignition missing not internal fuel map issues.

This is true, but not quite sure what the hell it could be then. The ignition system has all new OEM parts, Fueling seems correct otherwise, and using the PFC i can see that the MAP voltage is still correct. PFC is still running a safe tune so am getting 9.9 afrs at WOT (this will change when I get my J&S safeguard and datalogit ). Well know that the stock ECU richens up to as much or more so what gives? Out of interest Jim, have you had a wideband installed while you had the stock ECU? Would be interesting to know which point your ECU starts to richen. Maybe it does stay lean for a bit.

Would TPS affect the ECU's ability to see boost/richen boost on sudden WOT condition??

[Benckj]

I didn’t install a WB while running stock ECU but have run on the dyno before and it runs pig rich. Think I even cracked into the 7’s with OEM which convinced me to go aftermarket. The TPS won’t affect AfR’s as this is primarily controlled by MAP and RPM.

One thought on your WB is the grounding of the controller in relation to ECU. They are very particular on grounds so possibly it’s a sensor or cal issue?

[4CylinderSpecial]

I didn’t install a WB while running stock ECU but have run on the dyno before and it runs pig rich. Think I even cracked into the 7’s with OEM which convinced me to go aftermarket. The TPS won’t affect AfR’s as this is primarily controlled by MAP and RPM.

One thought on your WB is the grounding of the controller in relation to ECU. They are very particular on grounds so possibly it’s a sensor or cal issue?

I did happen to recal the WB sensor yesterday before running the PFC again and it seems fine. Sits fine at 14.7 at idle as expected and is behaving like how it usually has. My TVSV is unplugged and capped, could this cause an issue?

[Reubenh]

I doubt it will be an ECU issue. Is your fuel pressure dropping? That's what I'd be starting with.

Keep us updated

[4CylinderSpecial]

I doubt it will be an ECU issue. Is your fuel pressure dropping? That's what I'd be starting with.

Keep us updated

Perhaps it is? Although going to the Power FC has it running nice and safe again. Will need to experiment more but am looking at dropping engine and doing cambelt etc so might take a while to investigate. Will probably do a new fuel pump at the same time...

[Benckj]

I wouldn't have thought the FP would not be the issue unless for some reason the stock ECU was stuck in 'low volt mode'. This is primarily driven from the resistor packs and many aftermarket systems run full mode all of the time. Might pay to check these out as its not the pump itself.

As a mod to consider look into aftermarket pump regulators. Some of these like the one I installed is adjustable and has a gauge so can monitor FP performance. I've used it many time including when my pump decided to s**t itself and just happened to note how the pressure was fluctuating at idle. Pump died very soon after and I confirmed the fault when jumpering FP & B+ without any pressure at all.

[4CylinderSpecial]

I am going to replace my fuel pump soon with a DeatschWorks 255lph that I picked up. Will see if that fixes the problem. If it doesn't, I'll have a look at disabling the fuel pump resistor and solenoid combo as this can sometimes cause the issue. Wonder if the PFC uses this solenoid like OEM or ignores it.

[GDII]

I am going to replace my fuel pump soon with a DeatschWorks 255lph that I picked up. Will see if that fixes the problem. If it doesn't, I'll have a look at disabling the fuel pump resistor and solenoid combo as this can sometimes cause the issue. Wonder if the PFC uses this solenoid like OEM or ignores it.

Disable the fuel pump resistor first. Easy as unplugging and sticking in a thick wire to the plug to bridge the pins. Much easier than messing with the fuel tank. Or you can jump FP and B+ in the diagnostics port to test that running the pump at full speed all the time works.

[4CylinderSpecial]

Disable the fuel pump resistor first. Easy as unplugging and sticking in a thick wire to the plug to bridge the pins. Much easier than messing with the fuel tank. Or you can jump FP and B+ in the diagnostics port to test that running the pump at full speed all the time works.

Logically this is the right thing to do lol. Was just being lazy as have a low tank of gas in prep for the drop. The pump is now 23 years old I'm keen to replace it anyway.

However since I can see if it's not richening even in 2nd I might just go for a quick trip around the block this weekend and confirm. Will be interesting!

[4CylinderSpecial]

Disabled fuel pump resistor and tested. Still didn't richen and J&S lit up like a Christmas tree. I promptly swapped back to my Power FC and no issues again...

[4CylinderSpecial]

Well. After the nationals and my engine work I plugged back in the stock ecu just to test. Interestingly it now richens all the way to 9.0:1 on the afr gauge. I'm suspecting the stock fuel pump caused the issue but it is odd how even if the stock fuel pump was dying, the power fc could still get it rich as...

Anyways I will monitor on this ecu but that is an interesting note.