4cyl Intermittent Power and Throttle Response Loss at Temp

[92BabyBlue]

Hey everyone,



I've been using the forum for months trying to fix this issue and have struck out more tones than I'd like to count. Got a laundry list of things I've done to it but still having the same issues as when I started this overhaul back in February. Only posting here in electrical because there's not much left mechanically that could be causing issues. Anyway, here's the details.



Problem: Once I reach operating temperature and at higher revs, typically getting up to highway speeds, the engine will start to sputter and then I'll lose all throttle response before she dies. I can then turn the vehicle off, start it right back up and limp home in 2nd gear and low revs.



Here's everything I've done to it:
-Timing chain

-Oil pump, water pump, fuel pump

-Distributor, ignition coil, sparks and wires
-Battery

-Fuel injectors

-Air filters and fuel filter

-Radiator and Thermostat, all coolant hoses

-Head/Intake/Exhaust Gaskets

-Cyl Head serviced and checked for Valves seatting properly
-EGR Delete
-Fuel Injector & TPS Wiring Harness Crimp Splice



Probably easier to make a list of things I haven't done. But, she's in the shop now (Pride lost) and they're having a hard time even reproducing the problem. He says they pulled 3 codes from the unit (EGR, air intake Temp, and an unlisted code he couldn't determine). They seem to think a 30yr/o processor could be bad but they've got no way to pinpoint problems like that.



At this point there's no way I'm throwing in the towel, sunk cost fallacy be damned. Really thought it would be the bad wiring harness crimp but when I got in there a previous owner seemed to have already done it (a shoody job at that so I re-did it anyway) but still no luck. She runs and sounds like a champ before she dies on me so I'm really grasping at straws now. This being my first foray into automotive work I know there's something stupid I'm overlooking and would really appreciate y'alls help.



Anyway, she's a '92 4cyl 5sp manual with ~178k miles and I use it as my daily so while my bike commuting has improved greatly this year I'd really like my baby blue back soon.



Thanks in advance everyone.

[89'HBV6]

A few thoughts...
- fuel pressure check when hot?
- replace ALL vacuum lines, ALL? Rubber becomes more flexable when warm and can start sucking air thru dryrot cracks.

Seems to me it's a heat related problem, right? So, think about what can be affected by heat, that can lead to this problem.

Also, what's that 3rd code? It may be important.

[dvdswan]

More fuel..

IAT sensor (inside the air cleaner) can cause issues. Plus its a code. Depending on which code popped 1st, the others can cascade off of that one. Coolant sensor for the ECM can cause this as well.

Does this only happen when at operating temp or sometimes at op temp?

How high of revs?

[tannerg1223]

Would like to follow along on this thread- my 96 is cutting out under 3k rpm’s and will die if I don’t feather the throttle. Truck runs great over 3k… I’m running a Nismo r4 cam and have recently installed the 240sx manifold which is when my problem started.