One of the most dreaded issues with the GT86 seems to be the camshaft correlation faults, with a wide range of codes from P000A to P0020 this problem can leave your FA20 feeling sluggish. Don't worry though, many others have had the same issue and it's not a mystery as to what's actually going on. The reason the ECM sets these faults is due to a discrepancy in the crankshaft and camshaft timing. This can be caused by either a faulty OCV solenoid, misaligned chain, a faulty camshaft sprocket, and sometimes the ECM.
Here you can see the VVT designations as described in the service manual. Bank 1 is always on the side with cylinder 1, so B1 is on the passenger side and B2 is on the driver side. Bank 2 Sensor A is the first sensor on B2(intake cam), and Bank 2 Sensor B is the second sensor on B2(exhaust cam). With this information, you can see our P0018 Bank 2 Sensor A code is directed at the driver side intake cam.
Step 1 - VVT Initial Position Learning Values
Whenever a new ECM is registered to an FA20 equipped car, it has no stored learning values for the VVT sprockets. Even new cars from the factory need to perform a drive cycle before the ECM can "learn" the sprocket positions. Once these values are stored there is no way to erase or reset them, small adjustments can be made over long periods of time but that's it. This is why it's very important to diagnose these issues properly the first time. If you install a new ECM before the cause of the failure is repaired, you will need to replace it again and they are not cheap. Be prepared to transfer your tune software or license to the new ECM as well.
In the image above you can see what our problem cars learning values were, and right away you can tell VVT #2(intake cam Bank 2) is out of the specified range. The VVT #1(intake cam Bank 1) looks good and so do both of the VVT Ex(exhaust cam) values. At this point we know we have a problem with the driver side intake cam sprocket timing and we will need an ECM at the end of our repair. Let's move on...
Step 2 - VVT OCV
The first part of the VVT equation is the oil control valve. This 2-wire solenoid is commanded via duty cycle by the ECM to control the VVT sprockets. The solenoid presses the button in the center of the sprocket, opening the passage and allowing oil to flow inside. The oil pressure from the engine flows through the camshaft and into the sprocket chambers, forcing the inner section (attached to cam) to "advance" in relation to the outside shell (attached to the chain). The duty cycle determines how far the solenoid opens, which performs either an advance, hold, or release action.
So you can see just how important the OCV is, so let's start by marking our problem part with a sharpie as "B2A". Swap the Bank 2 sensor A solenoid and the Bank 1 sensor A solenoids, clear the ECM memory and perform a 10-minute road test. After the road test check for any pending codes, if you now have a P0016 then you have a bad OCV and it should be replaced. However, if you have the P0018 again like us then keep reading...
Step 3 - Inspect Timing Chain
Another possible cause of the cam correlation issue is jumped chain timing, I've seen it several times already and even on new unsold cars still on the lot! You will need to drain the fluids and remove the radiator and front cover to inspect the chain. Once you get access, turn the crankshaft clockwise until the key is at 6:00 and the triangles on each sides sprockets face each other like the image above. If any mark is not aligned properly then that is probably the cause of your issue, I would recommend replacing both sprockets and the tensioner on the affected side. There is no way to tell what caused the jump, and the amount of work it takes to do this repair are the reasons for my suggestions. You will need an ECM to correct the learning values for this failure.
However if your timing is aligned properly like ours was, keep reading...
Step 4 - VVT Sprockets
You can see in the picture above that there are many small parts inside the VVT sprockets. I do not know what part fails inside these gears but 90% of the time they are the cause of cam correlation issues. After verifying your chain timing is correct in the previous step, lock the tensioners with appropriate tools then go ahead and remove the chains CAREFULLY with the marks still aligned. The chains and guides are universal so you don't have to worry about mixing them up, the tensioners however, are specific. Once the chains are off, turn each sprocket by hand and be sure the cams feel smooth an free within the unloaded range. If all 4 cams feel the same and you dont find any damaged parts, go ahead and replace BOTH the intake and exhaust sprockets on the affected side. Again, you dont want to re-do this repair in the near future so be sure to eliminate the odds of accompanied component failure. I've learned this the hard way.
Reassemble the car being sure to double check the sprocket knock-pin alignment, torque the sprocket bolts, set the timing and verify chain is in the guide grooves, tensioner bolt torque, then clean ALL of the old silicon from the cover and mating surface. Install 4 new o-rings and put down a 1mm bead of silicone on the cover, get the bolts ready and wipe the engine surface 1 last time being sure no oil is there to cause a leak. Install the cover and torque the bolts accordingly, assemble the rest of the car and fill fluids. Clear the ECM memory and run the engine to purge the cooling system, then go on another 10-minute road test. When you return to check for pending codes, the P0018 should be there waiting for you.
Step 5 - ECM
The final step in this repair is to replace the ECM. The GT86 ECM is located behind the glovebox trim on the passenger side. You will need to remove the glovebox, and the surrounding trim to access the module. It is attached to a metal bracket and two 10mm nuts hold it in place. Once you install the ECM you will need to register it to the car, this process takes 30 minutes so have the battery on a charger. Once registration is complete, go ahead and do another 10-minute road test. When you return to check for pending codes again, at this time there should be nothing.
If you decide not to replace the ECM, be prepared to reset the check engine light every two trips. Also be aware your car will be down on power since the ECM will be limiting you to about half the VVT operation. I hope this helps and don't hesitate to leave any questions in the comments or suggestions.
What is corner balancing?
Corner balancing is the process of shifting weight around in the car and adjusting corner heights to obtain a desired 50/50 cross-weight percentage, ultimately making the car perform equally in left and right turns. The weight you shift in the car is usually the battery, but can also include ballast, the fuel cell, oil accumulators, and fire system tanks. You want to place these items in areas of the car that is lighter than the rest to off-set the weight from the driver and drive-train components. Ideally, these items should be kept within the wheelbase of the car, and not placed in the far corners of the trunk or engine bay to prevent a pendulum effect. After relocating everything possible the ride heights are adjusted to create a 50/50 cross-weight percentage.
When I installed the BC Racing coilovers I decided not to do the corner balancing right away. Instead, I started with the weight reduction and testing spring rates, this way I didn't need to get re-adjustments after every change. Once I had removed a lot of weight from the car and settled on the 5k springs, I set an appointment with Bret at Yawsport for corner balancing. I also asked him to do a thorough inspection of the car to verify everything was optimized. We made the 50min drive to his shop in Ramona CA to drop off the car, and anxiously awaited his updates...
The following day I get a message that the balance was pretty far off, (maybe 3% if I remember correctly) and he is unable to correct it any further due to lack of adjustment in the rear. I'm told I need to purchase ANOTHER set of Swift springs since I was sent the 7" instead of 6". When I installed the Swift springs last year I did notice that they took up almost all of my adjustment to set the ride height, but I'm a noob and didn't think anything more of it at the time.
I emailed BC and was told to call their tech support hotline, I tell them my situation and they begin to look up the part numbers to verify I was sent the correct springs. It turns out that they did send me the correct parts listed in their catalog, and because my springs were installed we couldn't do an exchange. I'm not sure if this is a isolated problem for me because my car is much lighter than stock, or if anyone else with a Yaris and these DR's have run into any issues like this.
I told Bret to do whatever was necessary to get the car balanced, he ordered and installed the new springs and had the car balanced by the following day.
I was a bit annoyed about having to buy a second set of the same springs, and Bret gave me the appropriate "I told you so" talk in regards to testing a new set of coilovers. He had warned me plenty of times, but I wanted to test something other Yaris owners could attain easily with good results. Well, that's how it goes I guess, all is well now and It didn't cost too much to do some valuable R&D. haha.
You can see in the photo above that we are now at a 50% cross weight with a driver ballast, and everyone mentioned it was going to be a huge improvement. Bret gave me a list of improvements I can do to the car, including getting that LSD as my main priority. We talked about the future of our local SCCA region and how we can make another round of spring rate changes next year when we know more about venues.
So what are the differences?
On the drive home the car felt amazing, it was like the front and rear suspension were working together now. Before, anytime I went over dips or large bumps it felt like the back of the car would rebound off the bump pretty hard. This is the reason I had to turn the dampers down to 5 clicks to drive it on the street, but now I was able to keep it at my race setting and not get beat to death. Interesting.
Our first race after the corner balancing was the 2018 Match Tour, and I noticed right away that the car felt loose. I was struggling to hold the car composed through the slaloms, but it was easily correctable so I kept rolling with it. It wasn't until my co-driver spun the car that we made some changes, we turned the rear damping down from 16 to 12 and that seemed to solve the problem. We will continue our tuning process at the next event and refer to the results to verify we going in the right direction. You can check out the Match Tour video below:
Coilovers are an amazing tool for tuning a car's suspension, but don't think for a second that you can just install them without ever messing with them again. If you're buying coilovers to slam a car and go hard-park at meets then that's fine, but to me, that seems like a waste of such a functional product. For those that want to race you need to properly install and set preload, test-n-tune the dampers, figure out spring rates, and corner balance the car. Everything you change will affect how the car behaves, so be prepared to repeat this process as your project advances. I highly recommend you get in touch with Bret and discuss your suspension goals, and listen to what he recommends the first time so you don't have to learn the hard way like me.
The SCCA Match Tour is essentially a National Tour style event with an index challenge on the following day. This event started for us on Friday, where Robert and I did some test-n-tune runs on the small practice course. I did 2 runs and Robert did 6 runs, ultimately putting down a faster time than me. We both thought the car felt good and moved on to check-in and tech inspection because we are in the Prepared category this meant we had to get weighed. The SCCA has "minimum weights" that the Prepared and Modified classes must meet based on engine displacement and aspiration. The limit for our car with a N/A 1.8L engine is ~1500lbs, so we hit the scales knowing we had a TON of room for error.
After handling the legalities, we headed out to walk the course together. I've walked many courses over the years, but this time was different. Robert has a way of stopping and analyzing the course in different areas, noting elevation changes and discussing alternative methods of attack. This is something I've never seen before, as I normally just walk the course to take mental notes of where to brake and turn lol. With Friday's activities completed, we packed up and went home.
Saturday morning we walked the course again, went to the drivers meeting, then observed the first heat take their runs. We had to work heat 2, which seemed to last forever due to timing issues. Heat 3 was finally up around 11 am, so we pulled the car into the grid and set up the GoPro. We were the second car in line so I had to get ready right away, I got strapped in while Robert verified tire pressures. On my first run, I was surprised how loose the car was at speed, somewhere in the middle of 3rd gear the rear of the car felt very light. This caught me off-guard at first but it seemed to be easily correctable, so I just rolled with it. Then once Robert spun the car at the finish, we agreed to turn the rear damping down from 16 to 12. This seemed to help and we finished our runs for the morning, me with all dirty runs and Robert having one clean time. The event shut down for the lunch break and we took some time to reflect on our situation.
During our afternoon heat, we decided we had nothing to lose and just tried tossing the car around the course and not holding back. It was a bit warmer now and the car was still loose, so Robert did some tire pressure tuning to real it back in. We did the best we could to log clean, fast runs for the afternoon...but we were still way off the pace. I'm not sure if the corner balancing shifted how the car behaves or if my tires are starting to fall off...but the car behaved vastly different. Comparing my times from the previous event, either I was one second slower than usual or Ian in the BMW was one second faster.
I also took a look at the overall PAX results, and I placed 124th. That's only about 20 spots slower than my usual pace at the local events, so maybe we didn't do too bad. Of course, we could have gone faster, but I think having to relearn and retune the suspension set us back in our efforts to drive the car at our absolute best. That's a testament to how much the balance was off previously, and verifies everyone's statement about how different it was going to be. Also, there is the fact that we don't run Hoosiers or any boost, yes we have a light car but that alone is not enough for Prepared class. I just can't justify the cost of those upgrades right now, I like having a reliable "do anything" car more than anything else.
Huge thanks to Robert Stangarone for driving with us, I learned some new course walk techniques and had an absolute blast chasing the XP field with him haha. This guy is a real asset to the racing community, very knowledgeable and always willing to share what he knows or help others in any way. I highly recommend co-driving with Robert, we could all benefit from gleaning some of his qualities. Thanks, man!
In my time as a technician I've encountered some strange issues, from defective new parts to ECM software bugs. Most of the time theres something obvious telling you there is a problem, like a check-engine light or noises. But on rare occasion, you get a customer that is very aware, and a car that only malfunctions ever so slightly in a brief operating window. This brings us to my very first Tech-Tip, how to capture ghost fault data.
In the picture above you can get an idea of how modern engines operate, there are many sensors providing feedback to the ECM(Engine Control Module) to maintain optimum performance. Most sensors themselves are also monitored to ensure accuracy, they are required to respond a certain way within a predetermined time frame. I'm sure you can guess what happens if a sensor responds too slowly or incorrectly, you get a fault code and a check-engine light. So what about those issues you feel but never get any red flags from the ECM?
Capturing and Analyzing Data
One of the most important tools I use everyday is an OBD scanner. The most accurate way to analyzing data is by logging in graph view, otherwise you would never see the large variations in sensor output that are so close together. Look at the RED line in this picture, that is the A/F sensor signal and you can see it's going a bit bonkers next to the vertical FLAG line. Now look at the BLUE line, that is the REAR O2 sensor and it seems to be reacting to the same influence upsetting the A/F sensor. At this point it's safe to say something is causing a erratic lean condition, so now you should be testing your fuel pressure (ours was 52psi, good). Next I tested the alcohol content of the fuel, and it was exactly 10%, good. Knowing our fuel system is in good shape, I went back and monitored manifold vacuum, -9.6psi at idle, -10.2 at 2500rpm, and -12.0 on decell-all good here. Now I need to check a few other graphs...
Here we have the BLACK line showing the MAF sensor and the GREEN line showing the THROTTLE. The MAF signal looks very smooth and follows the pattern of the throttle, showing the increased airflow then returning to idle flow. At this point I did a smoke test on the intake manifold and the exhaust manifold, revealing no leaks. I did another drive cycle monitoring the VVT, EGR, and EVAP, and these systems seemed to be affected by the surging but still very much operational. I called the dealer help-line and informed them of all of this data, and they were confused as well.
1-A/F sensor-no change
2-EGR valve-no change
3-Evap purge solenoid-no change
4-PCV valve-no change
5-Accelerator pedal-no change
At this point I just decided to grab a loaner car and start swapping sensors, since talking to tech-line and ordering parts was taking ages. I started with the MAF sensor, swapped in the part and went out for a drive. I didn't feel anything going around the block, so I went around again and nothing. I went around the city a few times and never felt the surging again, so I logged the data again and behold...the A/F sensor signal is clean!
So what can we learn from this so we catch it faster next time?
First I would say trust your instincts. I knew there was something affecting the A/F sensor and the car could have been fixed a lot sooner if I swapped in a known good MAF sensor first. I guess the MAF sensor can be faulty even if the signal looks good, witch is strange. I did everything possible, reached out to my peers, then started hypothesizing. Kinda sounds like life right? Take a look at the photos below showing the difference between the production part and the new part. When I fist saw the difference I assumed it was some type of update to improve flow, but I was wrong.
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