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L28et not rev'ing past 4800 (like a wall) I have searched and can't find anything. I'm sure there's info on it though. I have a 71 240Z l28et megasquirt hx35 water meth 1.4bar low boost high boost is 2bar runs and drives great but only wants to rev to 4800. I recently put this engine together about 18,000 miles ago and it used to pull hard way past 5K (5500-5800 is where it would normally start to fall off at but I could push it to 6-6200) only thing that has changed is I've gone to sea level adjusted the tune accordingly 24 degrees of ignition timing 10.8 -11.2 afr (only thing I've changed is fuel). I've been going easy on it because I was driving it across the country and don't have a garage to work on it and was the first time Ive turned down the Boost from 2bar. Normally I don't rev it that high unless I'm racing or driving it hard (on track) and haven't really gotten on it really hard since before I drove it across the country... what I think is happening is my cam timing is advanced... while driving it across the country one morning I got up to start it to let it warm up and it backfired through the intake and idled backwards for a couple of seconds (sounded horrible). Quickly turned off the ignition checked everything and went to start it and it started and drove fine. That was about 2800 miles ago. Full Boost @ 3800 feels like it should be at 4500 or even higher. In order for me to check ignition timing on the crank I would have to put a dial indicator in cylinder 1 because there's no key way in the underdrive pulley. it's only been dialed in when the engine was first assembled for the offset to megasquirt. this is what makes my dilemma a little harder to check cam timing. I can't just pop up off the valve cover and check crank to cam timing. I may need to just go buy a dial indicator take off the valve cover and go from there and start turning the engine over. Anyway anybody else have this happened there engine... engine rotates backwards and the timing chain jumps on the cam? Ideas.. thoughts . Thank you for your time ahead of time and please go easy on me.

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Posted (edited)
On 6/3/2018 at 2:31 AM, Nicksturboz2 said:

 In order for me to check ignition timing on the crank I would have to put a dial indicator in cylinder 1 because there's no key way in the underdrive pulley. it's only been dialed in when the engine was first assembled for the offset to megasquirt. 

 

Wait - what?  Am I reading correctly that you have a crank pulley with no keyway?  Where are you getting your ignition timing from?

Edited by TimZ

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You could also just do it the old fashioned way and find TDC with a piston stop. Just need some kind of pointer on your crank pulley, even if it's a makeshift one. And timing tape helps but isn't necessary. Then you'd be able to easily verify ignition timing and cam timing. 

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 so I'm getting my ignition signal from the crank and that's how we set it up in the beginning. we use a piston stop marked top dead center on my reluctor ring 1/8 in in front of where the sensor is and that Mark is gone. That was before I drove it from New Mexico to New England. I've never had a problem with the car. I will say this I've had many turbo engines but they've all been hydraulic heads. I've done a valve adjustment on it and it seems to run fine... may e the valve adjustment could be causing these issues if it was adjusted too tight. My last engine I put over 50,000 miles on making over 350hp with no keyway in the crank with no issues banging it off rev limiter road racing time attack all kinds of things so I don't think that's an issue.  I really think it's a cam timing issue from the engine running backwards for a couple seconds or the valve adjustment is too tight. That's the only thing I can think of. I really thought this engine would be more rev happy than the hydraulic head. Here in the next day or so when I get a chance I'll do another valve adjustment just to check it. unfortunately I'm working in a parking lot while traveling and can't work on it in a garage.

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