B18C-Hatch-Turbo

I have a JDM B18C and it throws a MAP and TPS sensor code intermittently; I have checked the MAP and TPS sensors and harnesses and they are good (followed this link)

http://troubleshootmyvehicle.com/hon...e-map-sensor-3

The codes always come on together; never 1 then the other and there doesn't seem to be a pattern (i have checked the wiring and sensors with and without the code)

I have cleaned the TB; IACV (hi and low speed) replaced the o-rings, new plugs and wires and followed this diagnostic: https://honda-tech.com/forums/honda-prelude-4/end-all-idle-surge-bounce-etc-problems-thread-1979500/

Is there anything else that could cause this? I am at a complete loss

B18C-Hatch-Turbo

the car was sitting for almost a year; could the gas have gone bad and cause this?

B18C-Hatch-Turbo

112 views and nothing???

So just checked the grounding - all good
did a valve adjustment - couple exhaust valves were out .001" and all within spec now
Timing belt is on correct teeth
did a compression test 195, 200, 205, 210 psi (JDM @ 10.6 compression ratio)

any suggestions on what do look for next? Can i even check ignition timing with a CEL

B18C-Hatch-Turbo

just doubled checked for air in coolant - nada

bump

SolScifen

are the plugs on the sensors loose? maybe a bad connection?

does it actually run bad, or just throw the codes?

fcm

Same question, "does it actually run bad, or just throw the codes"?
I also agree, because it is intermittent, I would make sure terminals are tight, best way is to depin the female terminal, inspect it for corrosion and carefully "tighten" the pin up, re-pin and see what happens. 94

B18C-Hatch-Turbo

it runs bad when the codes are one; lumpy as if it's missing - and removing the connectors doesn't change how it runs at all

I double checked the senors/connectors/wiring and all good but this time i was able to get it to temp without a code. I checked the ignition timing and it's perfectly on 16 deg.

B_Swapped93

can you try a new map and tps they're like 5$ for both at junk yards around here D-series ones will work btw.

B18C-Hatch-Turbo

i'll try look for a new sensors but still don't think they are the root cause.

I took it for a drive and noticed that my brakes are not engaging until 1-2" from the floor; pedal isn't spongy and the pedal does return to starting position. I can pump the pedal which causes engine to rev but during the drive after a hard stop the car just died as i pull off. I turned the car off and waited a little it started up and ran with out any codes...could this have something to do with it?

Garage_Spec

In for the same issue only mines just throwing low tps voltage, unplug map and engine runs smooth. Have also checked about every possibility.

B18C-Hatch-Turbo

so MAP and TPS let the ECU know about the mass flow and it adjusts the timing so maybe it's throwing these codes because of incomplete combustion...my thinking is the ECU is blaming the sensors but this could be do to the distributor or fuel injectors going bad???

today I started the car and no problems; run up to temperature with very little idle fluctuation - no codes

B18C-Hatch-Turbo

poured a bottle of seafoam in the tank...cranked and ran perfectly - brake feels better everything ran smooth like it should. Thinking now may have just been carbon buildup/dirty injectors?

highly recommend seafoam; going to do the intake manifold this weekend. Might help you https://honda-tech.com/forums/members/garage_spec-999877053/

Garage_Spec

I have replaced my injectors but they were used, maybe I should try that. My car runs decent but after 60 seconds it just dies. Possibly clogged filter or just dirty injectors?

B_Swapped93

INB4 rod knock from too much seafoam....

0tech@Eagle

If memory serves me correct, Aren't the TPS and MAP plugs the same (plug configuration)? Is it possible you have them swapped? (i.e. the TPS plug plugged into the MAP and vise-versa).

Garage_Spec

I still have not found a solution, yes they are the same but I labeled them before removing, plus the tps wires are not long enough to stretch to the map without it being obvious that it's switched. I have gone as far as checking ecu pins and even testing a separate ground. Nothing has worked so far, engine dies under a load even with map unplugged

HondaPartsHero

Garage Spec it might help to start your own thread just because your setup, car, engine etc might be different from the original. Do that and add all the details.

B18C-Hatch-Turbo

i just installed a new fuel rail and my injectors were really filthy; so i clean them and what little i could reach in the intake manifold (Edlebrock Victor x) and car has been running really well lately - I think it's got to do with combustion since they always come on together.

B18C-Hatch-Turbo

codes are back...doubled checked the input voltage and low and behold my ECU is putting out 3.7volts now (pin to chasis ground)

Any idea on what could be the casue of that? Is thinking the voltage regulator could be the cause wishful thinking and likely just have to get a whole new ECU?

B18C-Hatch-Turbo

So I was checking the power to the TPS signal and it was 3.7V however when i removed the MAP sensor it jumps to 4.7V - Think this points to a harness/short/ground issue?

Anyone know if the MAP and TPS share a ground?