Mercruiser 7.4LX MPI Throttle Position Sensor (TPS)

[tpenfield]

I got a TPS error code ( I think it was code 24) on my starboard engine (as I mentioned in my ECT Thread). I also got a MAP error code (I think it was code 33) I didn't write the codes down before I cleared them.

Anyway, I am seeing occasional high idle and surging from the starboard engine, so I'll go for the new sensors.

Mercruiser Part #'s are: (engine S/N's are in my sig below)

MAP: 864856A1
TPS: 805226A1

I know the MAP sensor is a GM part that you can get for a fraction of the Mercruiser price.

I believe the TPS is also a GM part. I have seen parts and pricing raging from about $10 to $90. I assume the really cheap versions are off-shore knock-offs, and the Mercruiser are just re-branded GM parts.

Just wondering if anyone has the GM cross-reference to the TPS part number, as I may try to source it by the GM number and not pay the 'marine price uplift'.

 

[Scott Danforth]

Both littlefuse and Honeywell as well as Standard motor products offer "angular position sensors"

Here is one spec sheet. http://m.littelfuse.com/products/magnetic-sensors-and-reed-switches/hall-effect-sensors/55250.aspx

here is another .http://m.littelfuse.com/products/automotive-sensor-products/powertrain/position-sensing/rotary.aspx

https://sensing.honeywell.com/sensors/non-contact-hall-effect-rotary-position-sensors/RTY-series

https://sensing.honeywell.com/sensors/non-contact-hall-effect-rotary-position-sensors

 

[Scott Danforth]

Newark has stock on the honeywell

 

[Scott Danforth]

I have them linked at work, these are the ones i could quickly find with the phone

 

[Scott Danforth]

if you pull the sensor off, there should be ink-jetted part numbers on it as well. usually you can find the original manufacturer of the sensor that way.

 

[Scott Danforth]

here is the link to the SMP site. http://www.standardbrand.com/en/products/sensors/

its java so you have to scroll down and click

sorry about the multiple posts....Admiral picked up a new puppy, and he doesnt have the potty training thing down yet.

 

[tpenfield]

Thanks Scott. I believe the code (24) indicates that the MEFI saw the TPS as being 'inactive'. So, maybe it is a connector issue, which I will check. Then I can probably get the #'s off the sensor.

 

[Scott Danforth]

I found this 853678T (replaced by 8M0097035) Merc TPS will cross to an ACD number of 213-912 or GM #17123852

However still looking for 805226A1

here is one on Ebay https://www.ebay.com/itm/NIB-Mercru...&sd=291260386096&_trksid=p2047675.c100623.m-1

 

[tpenfield]

According to my Mercruiser P/N searching, the TPS looks like this . . .



I did not see any like images in the links, but maybe I need to look deeper into those web sites. I did see the eBay links. :thumb:

 

[Scott Danforth]

https://www.google.com/search?q=sta...tLDcAhUHSK0KHVH4B6EQ_AUICygC&biw=1142&bih=862

looks like SMP TH42

 

[Scott Danforth]

FITS THESE

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[tpenfield]

Yup, the TH42 cross matches to a 805226A1 per their literature. Looks like it is a $25 sensor

 

[Scott Danforth]

yes (you may find it for less). and I believe the IAC is a ford Windstar sensor. havent crossed the MAP yet.

 

[alldodge]

Great info I'm recording the stuff. Not to side track but does littlefuse have a cross reference section, I'm looking for a cam sensor

 

[tpenfield]

I was able to cross-reference the Mercruiser parts to SMP (Standard Motor Products) parts

MAP Sensor: Mercruiser 864856A1 = SMP AS5
TPS Mercruiser: 805226A1 = SMP TH42

Mercruiser pricing would be about $290 total. The SMP parts were about $65 total.

I got a few IAC modules as spares. It is the Ford Windstar part, as I recall.

 

[alldodge]

Great info, have it all recorded, thanks

 

[tpenfield]

UPDATE:

I put the new TPS in and ran the engine . . . FAIL

The engine runs at a high idle (1800 rpm) , so something is not right. I hooked up the Diacom and I was getting a 2.7 - 3.1% throttle position, which is off a bit. Should be 0% or 0.7%.

I did test the throttle movement via the Diacom (engine not running) and I am getting the throttle position to go up . . . about 85% at full throttle. I did a couple of IAC resets to not avail.

So, I am wondering if there is an adjustment or something :noidea: I believe the throttle plates are closed all the way, just the TPS is reading slightly differently.

I'm back at my house for lunch and will be going back out to the boat in a while to try again. Maybe I messed up putting things back together.

 

[alldodge]

There are set screws under the TB, but most cases they never need to be readjusted. I adjusted mine because it was damaged. Look at them and see if the potting around the nut is cracked.

 

[tpenfield]

Thanks AD. I got it sorted out.

There were 2 set screws. I was able to get the TP down to 1.2% with the set screw and then I was able to loosen the sensor, tweak it and re-tighten it to take out the rest. 0% 0.55Volts

Here is the Diacom readout . . .



I then buttoned everything up and took the boat out for a spin. We have a big crew of people coming this weekend, and I was getting a bit concerned that I might have opened up a can of worms with the boat.

 

[tpenfield]

BTW - the original part was a 'CTS' brand sensor. Not sure if it is the 525 or 583 series.