Thread: Exhaust Manifold

my car only has 130k think the injectors would fail so early? and the ga injectors are spec to 10 ohm flat can I trust that reading of 33.7? the thing that gets me is the car runs like a champ and the engine loves to rev, but once i hit that 80/85 mph mark the engine cant take no more and the manifold gets red hot after a minute of driving. injectors even on rock auto are 45 bucks a pop plus that's a lot of work to do my self id have to take the intake manifold off and all that junk

Not super common for Nissan injectors, but could happen for sure.

You measured them...
Them all being the same type of screwed up does seem suspect...

A lean engine can feel very good. Although it would be VERY lean I'd think with those measurements. Maybe the ECU is compensating a good bit, but can't all the way especially once you leave closed-loop at higher revs (which I assume it needs to reach 85 PMH?).

what do you mean closed loop ( do you mean wide open throttle or top gear?) I believe im in the top gear (not overdrive) when I reach that speed. and that makes sense but what is causing it to run THAT lean

https://lmddgtfy.net/?q=ECU%20closed-loop

okay makes sense but what is casuing it to run lean? what should I check?

Seriously?
The injectors are the main suspect here. We've been talking about the injectors for the past ~8 posts. They are probably your issue. Until you convince us otherwise, we'll be talking about the injectors.

There are other reasons to run lean, like the MAF sensor failing or being dirty, failing O2 sensors, vacuum leak(s), other stuff.

But I specifically was talking about injectors in my latest post, and how they could be 3 times the normal resistance, causing only 33% of the fuel to be injected, and how that could possibly allow your engine to continue to run. I'm guessing the ECU is compensating and providing more fuel pulse to the injectors so you're getting more than 33% fuel until you hit open-loop control. But this is a shot in the dark, based on your latest injector resistance measurements.

Just because you told us that injectors are expensive, doesn't mean we're going to stop talking about them...

could failing injectors cause me to use gas? drove about 50 miles today used almost a quarter of tank at crusing speed of about 70? and I don't understand how if all 4 of my injectors were only allowing 33% of fuel the engine would run PERFECTLY FINE until its fuel throttled to 80/85 even at those speeds the engine runs fine its able to hold that speed but cant go higher

YES
High resistance in the injectors (30 instead of 10 ohm) means that the power circuitry inside the ECU wont be able to supply enough power to open the injectors fully at higher duty cycles. This would explain why the car won't go past a certain speed!

okay then I will change the injectors and see if that solves the problem thanks guys for the help!!!!

I get paid on Tuesday ill order a set of injectors and ill reply back to the post with my findings

You're right, it might not be the injectors. And they are tough to install, and a bit expensive. I understand the reluctance to replace them. Maybe you could find a better test to perform for them? Maybe rig up a fuel sprayer to add fuel at 85 MPH?
Or maybe make sure you get injectors you can return if they don't end up being the solution?

If you are doing injectors, make sure you get new o-rings (top and bottom) and have some petroleum jelly around to lube the injector o-rings. New o-rings are VERY important. Your current ones will fall to pieces once you remove them.