Hard Limiter at ~75mph
Thread Starter
Teching In
Joined: Aug 2019
Posts: 33
Likes: 6
Hard Limiter at ~75mph Hey everyone!
Picked up a 1982 Datsun 280zx with a lq4 or lq9, buddy thought it was an aluminum block to give you a heads up of what im dealing with and i haven't bothered to check which it is yet.
Theres a number of little issues with the swap but the car is somewhat drive able, the big one is the car hits a brick wall around 75mph. There is a definite very hard limiter that almost put my head into the windshield the first time i came across it. Anyone ever come across this before?
Some other general info on the swap
- front o2's (there are no rear) arent hooked up. Theres a fancy swap harness in the car that comes with the flat 4 pin connectors while the sensors in the manifolds are the square 4 pin ones
- I currently have a MAF low voltage code and the engine hunts at idle. (going to attempt to clean the maf/check the wiring for that one)
- the engine build itself is pretty suspect from some small things ive noticed, Balancer bolt was finger tight and almost falling out, front cover bolt holes for the oil pan are stripped out from when someone swapped a low profile pan on it, didn't bother to put a dipstick in it after swapping the pan so who knows how much oil is in the engine or supposed to be in it...
The engine will more then likely going to be pulled this winter to double check everything but figured i'd check here incase someone knows exactly whats up or where to look initially.
Thanks in advance!
Picked up a 1982 Datsun 280zx with a lq4 or lq9, buddy thought it was an aluminum block to give you a heads up of what im dealing with and i haven't bothered to check which it is yet.
Theres a number of little issues with the swap but the car is somewhat drive able, the big one is the car hits a brick wall around 75mph. There is a definite very hard limiter that almost put my head into the windshield the first time i came across it. Anyone ever come across this before?
Some other general info on the swap
- front o2's (there are no rear) arent hooked up. Theres a fancy swap harness in the car that comes with the flat 4 pin connectors while the sensors in the manifolds are the square 4 pin ones
- I currently have a MAF low voltage code and the engine hunts at idle. (going to attempt to clean the maf/check the wiring for that one)
- the engine build itself is pretty suspect from some small things ive noticed, Balancer bolt was finger tight and almost falling out, front cover bolt holes for the oil pan are stripped out from when someone swapped a low profile pan on it, didn't bother to put a dipstick in it after swapping the pan so who knows how much oil is in the engine or supposed to be in it...
The engine will more then likely going to be pulled this winter to double check everything but figured i'd check here incase someone knows exactly whats up or where to look initially.
Thanks in advance!
Launching!
Joined: Aug 2015
Posts: 206
Likes: 11
From: Duvall, WA
If the speed sensor input is connected to the ECU, then it is possible you're actually hitting the speed limiter. Who knows what they've done to the tune, and whether it's appropriate for the rear axle gearing in the car.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Likely the speed limiter in the ECU. Trucks/vans had some low speed limiters. The smaller tires and possibly shorter gears are lowering it to 75 mph.
You can buy O2 sensors with the right connectors and plug them in.
It does sound like there may be some harness/tune issues in general.
You can buy O2 sensors with the right connectors and plug them in.
It does sound like there may be some harness/tune issues in general.
TECH Regular
Joined: Feb 2002
Posts: 426
Likes: 45
From: ohio
The factory truck speed limiter is 100mph I believe. With the hearing of the 280 being higher numerically to the truck and having smaller tires you are more than likely hitting the stock truck limiter at 75mph
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
I have ad a couple of people I know put 4ish gears in trucks that had 3.42 gears and their limiter kicked in around 80 mph too.
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You honestly may not want to go over 75mph in it until you check and make sure the wheels won't fall off. Gotta love people who do 1/4 *** swaps. Not sure of it's worthy off half assed with the stripped bolts. Will be really cool once you get it straightened out!
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Teching In
Joined: Aug 2019
Posts: 33
Likes: 6
Thanks for the replies everyone!
Sounds like I should be picking up hp tuners and sorting this thing out tune wise. A friend has an aluminum 6.0 hes letting go for $200 that I'll probably pick up, do a quick once over and cam swap then drop into this thing so I know what I have is good. Missing the intake and accessories but I'll just swap mine over.
While I'm doing that can go through everything else and hopefully not find anymore cut corners.
Exhaust is a big one to fix aswell, looks like it was booger welded by a blind child, I kid you not the section where he merged the two banks together meets at a 90 degree angle... a T pipe if you will and looks like it was bashed with a maul for clearance. Top quality work haha
Sounds like I should be picking up hp tuners and sorting this thing out tune wise. A friend has an aluminum 6.0 hes letting go for $200 that I'll probably pick up, do a quick once over and cam swap then drop into this thing so I know what I have is good. Missing the intake and accessories but I'll just swap mine over.
While I'm doing that can go through everything else and hopefully not find anymore cut corners.
Exhaust is a big one to fix aswell, looks like it was booger welded by a blind child, I kid you not the section where he merged the two banks together meets at a 90 degree angle... a T pipe if you will and looks like it was bashed with a maul for clearance. Top quality work haha