Ecu shows almost 4K rpm while actually rpm is around 1500

this is a buddy's car that he is putting together, so I will list what all I know and the issue he is having.

car is 95 Supra with 2jzge block and gte vvti head, single turbo, tweakd harness, lq9 coils, Aem v2 6100.

i went over there yesterday as he said it would start but then backfire like crazy. So after checking mechanical timing to make sure we are good, I did the normal setup wizard and inputed all parameters. Once the car started the ecu was showing the rpm at 3800, backfiring like crazy, but audibly you can tell the rpm is more around 1500. Even when trying to lock the timing it still showed timing at what the timing is at 3800. I'm thinking it's a crank trigger issue, am I on the right track?

we ohm'd the crank and cam sensor and they were both in spec as well. I told him to pull the crank trigger wheel and check to see if he installed a gte or gte vvti wheel.

If you're seeing an engine speed error, The first place I'd look is at the engine position sensor settings. Does your AEM ECU have a trigger scope you can post pictures up of? Or do you have access to an oscilloscope at all, and can get some picture of the trigger signal waveforms?

I'm assuming the engine still has the original 2JZ trigger wheels installed?

I don't have access to a oscilloscope unfortunately. The block is a ge and the head is a gte vvti, so I'm not sure which crank trigger wheel he is running. I would assume that since the head is vvti, that the trigger wheel that needs to be used should also be vvti.

Unfortunately it's not very easy to run the 2JZ VVTi engine with the Series2 ECU. I can think of a few things that could cause headaches.

1. If you want to run VVT-i and use the variable cams, you need the VVTi crank trigger as well as the matching sensors. We've heard from customers who had problems trying to use mis-matched sensors and trigger wheels.

2. The ECU you have (AEM 30-6100) has cam/crank circuits designed to work with the 12-tooth crank trigger on the 94-98 USDM 2JZGTE engines, and that circuitry will not work well with the distributor-mounted sensors from a 2JZGE (non-turbo) engine or the newer VVT-i engines. If you are good at soldering very small components, AEM tech support can help tell you how to modify the circuit to work with the VVT-i sensors. If not, you can send the ECU to AEM and pay to have the hardware modified. This was addressed in the newer Infinity ECU, that hardware has some software-configurable filters and will work with either trigger pattern.

3. After you modify the vehicle-specific hardware to work with the VVTi pattern, you'll also need to configure the software to work. That engine wasn't popular in the US when Series2 ECUs were being developed, so I don't think there is an AEM base map with 2JZ VVTi settings in it. AEM tech support may be able to help with that but might also suggest using that ECU with the engine it was designed for, or suggest an Infinity ECU since we've done some work to make those play nicely with the VVTi engines.

Hope that helps,

SB

Thanks SB, that is a ton of help. I knew the v2 didn't support the vvti but I've heard of people running it. I've only had experience with v2 and non vvti. I will relay this message to him. Thanks everyone for the help