EFI 3.0 running too hot, though cooling system is copacetic

[buckmeek]

My 1969 912 has a newly installed EFI 3.0 with around 2k miles on a full rebuild, with PMO ITB's, Motec M84 ECU, Rasant cam/crank sensors and crankfire with Bosch COP, true sequential injection, 9.5:1 JE pistons, Carillo rods, Dougherty 993/964 cams, RSR seals, cross drilled crank from Ollie's, Carrera chain tensioners, SC fuel tank, SSI's, Monty stainless RSR exhaust, rebuilt gauges, etc, and I'm running a Carrera front oil cooler with a bigger Ferrari fan and Rebel Racing stainless cooler lines.

I've had the car street tuned at the shop who did the install, but haven't been able to get it in for a dyno tune yet as I've been out of town a lot, and finishing a suspension rebuild at home. The car is running well, it's a banshee, and I have no complaints other than one critical issue - whenever I push it for 30 or 45 minutes or more, or up a long hill (nothing super steep, i.e Stunt Road or Mullholland Hwy between Los Virgenes and Paramount Ranch, and under 5k rpm) it jumps up to 220f to 235f in 50f weather, and in the summer it even jumped up to 250f on the gauge once which was scary. I've had my trusted Porsche mechanic go through every single element of the cooling system, from thermostats to temp senders, oil lines, coolers, fan, fan relay, multiple test drives with a thermometer etc. He's confirmed that everything in the cooling system is functioning perfectly, and is therefore sure that it's something in the ECU program - so the only option left to try and solve the overheating issue is to get the car on a Dyno and iron it out.

Has anyone ever had a similar issue?

Cheers

[icarp]

You are describing a mismatch of the temp gage to the temp sender , 30* high in the reading.
also check the timing advance , 30* at 3000 rpm all in .

Ian

[buckmeek]

I will try that, but I've checked the engine temp with a laser thermometer in multiple places and it's only about 10 deg f off. it was reading 240 when the gauge was 250, still really hot.

[Tea Tray]

Sounds like an air flow issue if oil temp gage is reasonably accurate.
Turn fan by hand to verify belt grip.
All cylinder air flow tin in place?
Guide vane behind alt in place, if applicable?
A rag or other debris blocking engine oil cooler? Feel for air flow.
Electric fan coming on?
Electric fan air flow through cooler / louver sufficient?
Electric fan spinning the correct direction?

[chrisbalich]

I've noticed in my time with EFI that my car ran very cool when it was too rich and the temps came up quite a bit by leaning the mixture.
Run some logs and see if you're lean.
Other than that, I agree with Tea Tray. It sounds like an air management problem.

[Showdown]

It only happens when you’re moderately pushing the car…? Is it predictable and reliable?

If all the parts of the system are working then I’m inclined to say timing…

For it to be an airflow problem it would have to be pretty major as the fan moves SO much air. If the vanes weren’t reinstalled that could do it but otherwise it would have to be a pretty big rag or clog to halt that much air.

[chrisbalich]

Originally Posted by Showdown

It only happens when you’re moderately pushing the car…? Is it predictable and reliable?

If all the parts of the system are working then I’m inclined to say timing…

For it to be an airflow problem it would have to be pretty major as the fan moves SO much air. If the vanes weren’t reinstalled that could do it but otherwise it would have to be a pretty big rag or clog to halt that much air.

I was thinking big air leak more so than big air stoppage.

[Porsche 935]

If it's not a mechanical issue then your tune is either too lean or not enough timing. Or a combination of both.

[icarp]

As the others have said , it could be too lean , do you have an AFR gage?
Another thought , your fan looks redone , do you have the proper ratio of crank pulley to fan pulley.
Guide vane installed? when they rebuilt the engine , how bout the cylinder tin + proper mods, and all parts in the right place . Cylinders could be inverted .
Just thinkin
Ian

[al lkosmal]

One of the beauties of having EFI with Motec (or any other ECU) is that you can datalog....first thing I would do is datalog while this is occurring and verify the AFRs and timing at these high temps.

regards,
al

PS: Buck....you can email me the log files, along with a copy of your tune file and I'll be glad to review them and provide recommendations.

[manbridge 74]

Originally Posted by Porsche 935

If it's not a mechanical issue then your tune is either too lean or not enough timing. Or a combination of both.

Plus one. Start here…

[mb911]

Originally Posted by al lkosmal

One of the beauties of having EFI with Motec (or any other ECU) is that you can datalog....first thing I would do is datalog while this is occurring and verify the AFRs and timing at these high temps.

regards,
al

PS: Buck....you can email me the log files, along with a copy of your tune file and I'll be glad to review them and provide recommendations.

That is really nice of you. Love this community

[rswannabe]

Good suggestions so far. Confirm your gauge is reading accurately. Confirm your timing and AFR’s are good.

It can also be that the single carrera cooler up front is not sufficient to cool a hot rod 3.0 being pushed. The more HP your motor makes, the more heat it generates. I found that a single carrera cooler was not sufficient to cool my 2.8 SS in my ‘69 when pushed hard.

Do you still have your stock battery boxes in place? They block a lot of airflow to a carrera cooler. Cutting them out should drop your temps as well.

[Tremelune]

If the cooling system is working but just can't keep up, you might try a more serious fan:

https://www.americanvolt.com/collections/electric-fans

I plan to put a similar setup in my 1970, and I'm curious to see if you improve your situation...

[rswannabe]

One other thing to check, is your fan wired correctly so that it is pulling air through the cooler and not trying to push through it against the airflow?

I know it may sound dumb, but happens more often than you’d think. I’ve had both a Cobra replica and a restomod MG come to me with cooling issues that I resolved by wiring the fan to run the right direction.