05' Elise surging at partial throttle - Page 3 - LotusTalk - The Lotus Cars Community
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post #41 of 50 (permalink) Old 06-25-2018, 05:59 AM Thread Starter
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Originally Posted by Obeisance View Post
i would love to help with this if you want to be a guinea pig and can stomach some risk.

I've spent a lot of time thinking about the ecu code. I'll pm you my contact info in case you want to discuss further.
My appetite for risk is rather low at the moment. Hence opting to wait for rear clamshell removal. I just don't have any firm leads right now. Also looks like ECU's are $500~ used, $900~ pre loaded / new from MWR. All things equal I'd rather not risk the one thing I have the least ability to diagnose or fix.
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post #42 of 50 (permalink) Old 06-29-2018, 03:44 PM Thread Starter
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I went ahead and cobbled together a smoke test machine. The internet standard: e-cig wire + paint can + miner oil + air source. I checked post MAF just in case it was messy... oh, and it was. I included the ribbed intake tube. No smoke found after almost an hour turning the smoke on/off and looking over the entire engine. I also tested the vacuum lines (one way check valve removed) near the intake. No smoke found. Tested the vacuum reservoir - no smoke. I repeated this for the 'hot side' by directly hooking up to the tail pipe. No smoke except very small wiffs at the new exhaust band clamp - but AFTER the post cat o2 sensor - so not at fault. All in all that was my only 'find'. Was half hoping I'd see smoke around the header / heat shield... but no dice. The hunt continues for the phantom leak!

For kicks I swapped the o2 sensor plugs, because who the hell knows... as expected the cat came up to temp and the car hunted to the verge of stall. I turned the car off and reverted the o2 sensor plugs to their verified correct stock install - original symptoms returned, but car idled fine. So we can put the common 'swapped o2 sensor plugs' to bed for good.

What's the best way to find out my ECU software version? I called the dealer and the only records they have of updating my ECU were the standard VIN update for the CEL after your battery dies. Uncertain if that was a discrete patch or if that was an entire software flash... When I leave my door open, press the odometer reset button, and turn the ignition to full on (re calibrate gauge cluster) I see a date that's January 2004 and a v1.0 (roughly) - this isn't related to my ECU software is it?

I'm going to call a local shop on Monday that everyone likes and see if they can fit me in before my Lotus visit 7/16 @ 8AM (Auto Europe, Birmingham, MI)... half tempted to buy the ECU that's on the for sale section at $350 since the dealer is $150~ to just look at my car...plus driving there and back... so I figure 6-10hrs door to door.
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post #43 of 50 (permalink) Old 06-29-2018, 05:15 PM
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As far as I know, the numbers in the gauge cluster are not related to the ECU software.

The VIN can be rewritten without an ECU flash, but there has also been an ECU code update that allows the P0630 to be evaluated and set when the VIN is lost. Thus, this could have been or have not been a full code reflash.

You can figure out which calibration ID is on the car with OBD Mode 0x9 PID 0x4. The calibration validation number is OBD mode 0x9 PID 0x6 (this is calculated by the ECU each time it boots with a convolution over 0x6000 bytes at address 0x70000), so it will show if the calibration is corrupted.

OBD mode 0x22 PIDs 0x20e-0x211 will return ASCII characters that indicate which bootloader version is on the car: (16 ASCII chars, ex. "C121E0001F K0303")

OBD mode 0x22 PIDs 0x21c-0x21f report the calibration ID another way: Cal ID in ASCII (ex. "B121E0002H ")

OBD mode 0x22 PIDs 0x221-0x224 return the make, model and year that the ECU code is intended to run on (I think this is just supposed to identify the car): (ex. "Lotus Elise MY05")

More specialized tools are needed in order to read the ECU code and calibration directly.

I don't know what numbers are usual responses to some of these queries since I've never asked my car for these all of these PIDs.

I've had good experiences getting paint protective film replaced Auto Europe, as well as a tour of a new Evora 400. I hope you have a good experience too.
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post #44 of 50 (permalink) Old 07-06-2018, 06:36 AM Thread Starter
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I got a new 'known good' ECU in the mail someone on here was using for emissions testing on their 2005. The partNo on it was slightly different: C121E0001F, the original ECU was B121E0002H - cautious at this point I almost didn't install it. After a little googling it appeared both are acceptable so I disconnected the battery and threw it in, every so gently.

The new ECU seemed to run richer - which isn't shocking given how they seem to 'learn' over time. After first impatiently not letting it idle for 15min I got a CEL going down the street: too rich. Duh. AFTER letting it properly letting it idle for 15min the CEL did not persist and the car ran much better (aka not bogging as much). I went out for a test drive - original problem persisted. Boo. So it's not the physical ECU - still can't rule out software but I find that unlikely as this ECU is allegedly out of a car that easily passes emissions and was known to run well.

Data from the car being at operational tempratures - starting from stop light and going 30-35mph you can easily see the STFT and (new w/ ECU) LTFT adjusting:
https://drive.google.com/file/d/1XWW...ew?usp=sharing

Scratching my head what the source of the problem could be now.... fuel pump / fuel pressure regulator in the tank? wiring harness?

Last edited by yorkadam; 07-06-2018 at 06:50 AM. Reason: part No wrong
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post #45 of 50 (permalink) Old 07-23-2018, 06:53 AM Thread Starter
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Update:
Exhaustively checked continuity between ECU and primary o2 sensor. NO FAULTS detected. All wires correctly connected and not grounding out or broken connections. Doesn't rule out an intermittent fault as I cannot easily test with the car running. I also did not exhaustively check every pin on the same wiring loom fore connectivity issues with neighboring wires (hopefully I don't regret this in a year...we all know these decisions...).

After talking w/ Andrew @ BoE I didn't have much faith it'd work - but I paid a visit to Auto Europe in Birmingham MI. They were not exactly enthusiastic to solve my problem. To be fair on the rough SE MI roads the problem was hard to detect. So I re-created the problem, showed the data, talked w/ the technician. Long story short - I spent 8hrs in a waiting room and all they did was re-set my ECU (reverted back to original ECU after testing the new one I swapped in). Didn't appear they attempted to trouble shoot the issue at all beyond reading the write up I gave them. In the end they agreed to reprogram/reset the ECU. Unfortunately according to the tech my ECU was up to date, and he could not reload the software (ehhh - really?), only reset the ecu's memory. So 8hrs waiting and $260 later I tested the now re-set car - immediately the problem was present. Before leaving I was assured it was fine and the car was meant to be driven all out, not at partial throttle... right.

Not phased I proceeded to dig a little deeper into the Toyota service manuals. The procedure for testing the fueling system is to prime it and verify the pressure is held. If the pressure drops it basically tells you to inspect all things fuel. As all lotus owners know - the pressure did drop. So I caved and decided to attempt every 2005 Elise owner's nightmare: fuel pump and basket bits (pressure regulator, sock, and filter). Unlikely as it seemed there's still a chance it was failing partially due to a clog, electrical issue, etc. A week later the nightmare is over and the new parts are in. I let the car idle for a while after I adjusted the base idle speed (had to remove all the cables to get to the shear panel). Problem persisted... ouch. So what else could be leaking? Well the entire system by design could have leaks. I don't smell fuel - but having had longer / hard starts before I do suspect my "flow tested and cleaned" injectors... but I feel that's just throwing more money at the problem with no conclusive reason to suspect the injectors. What are the chances an injector could fail at partial throttle and instantly be fine at WOT or at high speed cam? There's a chance, but it seems fairly low... probably as low as the fuel pump being to blame in this scenario...

Shot off several emails to Lotus and Phil @ BoE. Curious what inputs are used for the short term fuel trim (STFT)... Does anyone here definitively know?

My problem is very specifically boxed: any scenario where the STFT is adjusting
30s after warm up
partial throttle very detectable
disappears at wide open throttle
disappears when the high speed cam lobes engage

Problem does not exist: any scenario where the STFT is flat lined
All sensors read normal - including the o2 sensor which then behaves in a more normal fashion in a steady state..
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post #46 of 50 (permalink) Old 08-23-2018, 02:19 PM
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@yorkadam have you made any progress?
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post #47 of 50 (permalink) Old 08-24-2018, 05:54 AM Thread Starter
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My current attempts to fix:
Replaced/swapped the injectors with known good new ones from Monkey Wrench Racing. Just in case my "cleaning/flow tester" was a sham. With the exception of the new injectors being louder, nothing changed. Last but not least I went ahead and swapped the bosch o2 sensor for a denso one. Again, nothing changed.

Out of the blue I ended up getting a call from Auto Europe saying they would like a chance to look my car again and feel they CAN fix it. Given their level of optimism and desire to get another crack at it - I agreed. They're supposed to call me back next week and arrange pick up of the car so I don't have to drive the hour plus to hurry up and wait.

While I wait for my second visit to Auto Europe I went ahead and scheduled up my third and fourth track days of the year. My problem seem to be getting any worse and i'll be within AAA towing distance of home... so I figured "nothing ventured, nothing gained" for enjoying my car on the track. At the very least if it does strand me - I'll at least have a solid lead.
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post #48 of 50 (permalink) Old 10-23-2018, 03:08 AM
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@yorkadam did the issue with your car ever get resolved?
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post #49 of 50 (permalink) Old 11-23-2018, 09:33 AM
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Bueller?

Another complication in diagnosing this behavior is that the ignition advance reported over the OBD port is not necessarily the value in use by the ECU. At low engine speed/partial throttle the ECU smooths changes in ignition advance to something like 1-2 degree changes per 50 milliseconds. The value in use is always approaching the value reported over OBD, but these values are not necessarily the same.

Also, if you'd like to talk about the STFT control strategy I can walk you through the ECU code or through a simplified explanation: https://www.lotustalk.com/forums/f17...ontrol-463664/
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post #50 of 50 (permalink) Old 05-27-2019, 07:16 AM
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Idle is not what I'd describe as erratic - see the data. You have to listen/look very closely to hear it - but it's most felt in the seat of your pants as a very not so subtle surging. I've been driving it for a year w/ no cooling system issue symptoms - including three track days. How subtle/consistent can this be? Also this issue is not tied to engine speed. It does however appear to be tied to the ECU's fuel trim when it's under partial load or idle. Thoughts?

The more I ponder how this problem came to be - it was gradual - but always kind of present during my brief ownership - and eventually culminated in the loud rhythmic popping on decelerations w/ hot exhaust. To me that gives a further nod to an issue somewhere on the fueling side of the fence since this could be a slow degradation of a pump or an injector.

Injectors are out of the car waiting for a friend to test / clean them - or worst case ship them out to a third party. Worst case I'll spend $100-150 to have cleaned injectors with verified flow rates. Regardless of the results though I'll have to make a trip to have the dealer reset my ECU so the old fuel maps can be ruled out as well. Part of me wonders if the aftermarket exhaust could be the cause of this - but the very consistent rhythmic popping situation would have been reported as a known issue w/ the exhaust if that were the case. I know what the fun burble and pops sound like - this is not it.

Any other sensor ideas for what could cause rhythmic surging/rhythmic deceleration pops?
have you had any luck with this? my 05 has started the exact same symptoms ~50k miles. It started around aug of last year was cruising at 60 and the car would just lean out (have an afr) for half a second then go back to normal at cruising speed. ran live data for tps and at the time it would do it it would go erratic with readings. so I replaced it as well as spark plugs. That corrected it for the 700 mile journey back home.

fast forward and I am suffering from startup troubles and car going extremely rich and surging throttle when not warmed up. and then the car goes rich and surges at cruising speed. I pull apart throttlebody take IACV off and clean it to look brand new. put it all back together and it runs flawless for 2 days.. goes back to the same issue. I order a brand new IACV from MWR install it and car is running like a champ again...... for 2 days. at the same time I also replaced the air filter. I am running a vf2 SC kit and bought the filter they recommended to replace with.

therefore in short I have a new TPS, new air filter, new iacv, and throttle body is thoroughly cleaned. however on partial throttle I am receiving intermitten 10.0 afr readings which is causing a jerk in the car and requiring a blip of the throttle to correct. my next theory is o2 sensor but it's looking like you've extensively looked into and not had issues?
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