93 16v, sound like its bogging. (the spark plug tips are the clue here, white or black?)
Rich or lean, compared to what? is the key word, answer, compared to normal and in what EFI mode.
(cold start. warmup, hot, Accel mode, closed loop , and limphome they are all different)
I am talking , Closed loop to Limphome. (pulling ECT does that, every time)
so when you are in closed loop you are in STOICH 14.7:1 AFR and limphome is 10:1 or just say very rich but more importantly, its retarded timing, (prevents burning the engine up)
Limphome mode burns the fuel in the muffler. not the engine.
the ECT disconnected, causes the
CEL to glow , that means it's in limphome, mode, and for sure if lean, the limphome forces hard rich AFR (air fuel/ratio)
going to limphome from rich causes. more rich, and more blacker spark plug tips and more misfire. Nasty misfire, even spark fouling ,extremes.
Relativity is key:
the issue is ,that we don't know where AFR was, before you pulled the ECT, no OBD1 scan tool. so we must guess, my guess is it was lean,
"NO load miss". might be that.? (buy the Rhino tool an see it mess up) see last link to see what you missed.(no pun)
(rich misfire or lean misfire?, lean is felt as a bog (dragging a weight, too rich misfire , is felt at rough firing engine,) i can tell this by driving easy, bog or the violent shake.
when you go WOT or accelerate the ECU goes rich to 12.5 :1 , via the MAF, and the 02 is shut down. ( this can hide a lean misfire, if spark is good. and fuel pressure)
The misfire at cruise, is in closed loop. light flat cruise, we look with a scan tool and see that it is. this first thing i do but you cant (lacking a scope)
if the engine is running lean, and you pull the ECT (is water temp at 180F ? or more?) and you pull this sensor, the ECT missing is causes 5v at the ECU and it immediataly goes to limphome.
the perception is more power, on a bad running engine lean engine, seen many a time. Pullng the MAF , does the same trick,
(ive not said fuel pressure yet, because i think your engine has full power WOT up hills. (36psi is normal)
on a good running engine, less power. that is how this works.
if you drop the ECT temp reading (by force ,(using a pot) ) to below 150F the ECU goes to cold start mode, and AGAIN, RICH, THAT IS LONGER Injection pulses.
That misfire, can be caused by lots of things.
The old ECU have very heavy fuel controls in that the fuel TRIM (LTFT) can go way to far. (cured in OBD2, 1996)
this is a bad thing, say when the o2 sensor is stuck. and allows the fuel TRIM (LTFT) to go way past 40%
just one exhaust leak near that 02 and cruise AFR will be wrong. (rich)
working with ECU/s blind is hard.
what i do is check my engine compression. ok good engine
and spark very carefully.
the o2 works. (IT Must swing at idle and light fast cruise. say 40mph on flat ground)
all sensors to the ECU good. ECT , IAT (if it has one, some 16v dont about 92/93) MAF.
EGT. exhaust gas temp.
when one says runs hotter, what do we mean, there are 3 places for heat to go.
MAKE power, waste it and burn hotter in the headers to the rear, or throw more heat to the water jackets.
EGT is max at Stoich. (that is because all the fuel is burning in side the engine and not outside, making more EGT)
http://www.sdsefi.com/techegt.htm
truly we dont know what is causing the misfire.
injectors leaking or partially clogged, (hidden by WOT , Enrich mode)
when you when over 3k RPM that sounds to me as Enrich mode, you said ,no load.
when you add lots of load to the engine ,it goes to enrich mode and the 02 sensor is shut down. on suz. this is easy with 1.6L. (tiny)
the engine will not overheat lean, (usually only retarded spark timing causes all the heat, to go to the water jacks, as the fuel burns way too late.
in a running right engine, this dont happen the fuel burns in the first part from TDC down.
runs hot.? (where)
is that the cylinder hot, the EGT hot or the muffler. (there is combustion flame too. heat and lean can be very very hot)
here is how big aircraft gasoline engine (1960) were run. (i pick this because they have really good facts and nice charts)O
Quote:The Recommended Leaning Procedure was a method used to lean those engines to a point on the lean side of what we now commonly refer to as peak EGT
This mixture setting also happened to provide the very best brake specific fuel consumption, coupled with very cool cylinder head temperatures.
Peak power is about 12.5:1 AFR (the heat of combustion does work, not wasted(as much), max torque)
stoch is 14.7:1 all fuel burned. and plenty of power (race cars run at 12(about) all the time.
leaner than that can cause problems with heat damage. and huge nasty NOX smog and burned valves. if the EGR is dead. (huge combustion heat)
finding good charts are hard,
but this air craft engine shows very nice one. you can see CHT and EGT at the same time.
note how CHT rises
your side kick runs for that RED STOCH bar to the left , rich at wide open throttle.
when you go to limphome its far left. and richer
if you were not at STOCH but were in fact far right, you can see what happens. (it can in fact go to the center, and make power) Relativity is key here.
PPH is pound of fuel per hour. CHT is cylinder temp sensor. EGT is exhaust temp, (outside engine !)
linked:
![[Image: pt1fig2.jpg]](http://www.gami.com/img/articles/bttf/pt1fig2.jpg)
conclusions: we dont know here we were, before the fast right foot(wot?) nor before, the ECT was pulled.
no scan tools.
if engine is good, spark good and injectors not leaking or partially clogged.
Id look for 02 dead. at cruise.
Id look at fuel pressure, and test the Fuel pressure reg at idle and wot. for power pressure variance, per FSM. THE ECU hates this to be bad.
Just because the power is good at 2000 RPM dont mean much , all gas engines make more power when too rich, 14.7:1 to 12: 1. so means zero.
seat of pants never means much unless you have misfire or tools to tell you what is going on, (wide band gauge 02)
(if engine and spark are good) its then down to bad ECU inputs. or bad injectors.
My 96 run funny, (tuned to max with scan tool and running data logs) but the EGR was dead, this ECU would send wrong fuel rates as i accelerated gently.
causing very odd flat spots, but wot was ok, because EGR is shut off at WOT.
all posts assume, Compression over 170psi hot. (or warm engine block)
all spark parts fresh. and timed right.
02 working,and swinging fast at idle and light cruise.
and the injector leak down test passing and the injector balance test passing. (they are equal)
WOT throttle perfectly good, and not misfiring or bogging WOT.
and last what you are missing
see the 31 data points in all Suzuki ECU? here? (out of 1995 FSM) see PID parameter 11. I bet yours fails this test .
and #13 LTFT, i bet its not centered, at cruise.
http://www.fixkick.com/ECU/Tech1/full_scan2.html
I use my scope to watch my 02. if blind, this allows me to see what it is doing.
The ECU on this car will go a little crazy with the 02 dead, or any air leaks anywhere near it, the outside air is 20% oxygen, and the sensor can not get the slightest whiff of that or BAM the 02 is now useless brick. (lies its buns off and cause wild cyclical issues, that Bosch explains, in their white papers.)
