loss of power when hot

FAQs and Howtos for electrical, lighting, Audio and other electronic projects or tweaks for your MX5.

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Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 3
Joined: Mon Dec 28, 2009 2:48 pm
Location: New Zealand

loss of power when hot

Post by jethro25 » Sun Jan 26, 2014 2:08 pm

Maybe this will assist someone. A few years ago I bought a 94 mx5 1800 with hotwire. Cheap cos it was running bad.Occasionally it would lose power after about 30min running but would jump away on about 3/4 throttle. Intermittent electronic fault? I'm a mechanic familiar with EFI, and yet it gave me a real challenge. Tried EVERY sensor test by substitution; no joy. Seemed to be heat or coolant related. Pressure test for H-gasket negative. Flushed system added sealer then flush then A/F. better but still not right. Found small water bypass into water pump inlet blocked. Cleared. Different car! Conclusion? Air was getting into system (tiny crack somewhere?) and settling round coolant temp sensor at rear of engine.Making ECU go into limp home.Overrides on full throttle.EFI cars MUST have full water around Temp sensor or crazy running results. clearing bypass allows good water flow round rear of engine, and sensor.Hope this wee adventure may aid someone, sometime.
the universe is always in balance.

Organic Ismar
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 2
Joined: Mon Sep 01, 2014 5:30 pm
Location: Dunedin

Post by Organic Ismar » Mon Sep 01, 2014 6:03 pm

Nice post
My cars doing something similar, First I thought it may be the coils or leads, but this is something to look into

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