2008 RZ4 400hp -MAP sensor fouls

[moore3]

On the above boat I’m having problems with my MAP sensor fouling.

It initially started last year at lake Powell. Did a long run 10-15 miles and then went to the marina to get ice. Was idling waiting for the ice to return and started back out of the marina when the engine died. I had a hard time getting it started again but it finally came back to life (most likely flooded). It seemed better after sitting over night.

Brought it home and investigated. Realized it had a MAP sensor that controls the air/fuel mixture. Took it out of the top of the manifold and cleaned it with MAF sensor cleaner, for lack of residual contamination. It worked fantastic after this for the rest of last year. Great, I thought, I’ve fixed that issue.
This year it began doing the same thing. I knew immediately to go straight for the map sensor and bought a new one too.
Now I can’t make it a full day with out a ‘stumbling’ issue of the motor. The new sensor acts the same as the old, in that, it works great for a bit but then fouls again.

I’m trying to see who has had similar problems and what they did to correct the sensor fouling issues.
At this point I’m going to replace the spark plugs and replace the wires too. I’m hopeful it’s not the injectors. Looking for others experiences.

Thanks in advance!



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[chpthril]

Id do cap and rotor as well.

Was the sensor fouled this year like last? Whats the look of the new sensor after a short time in and the issue returning? If there residue building quickly, id look into the crankcase vent system and maybe even do a compression and leak down tests.

[moore3]

Id do cap and rotor as well.

Was the sensor fouled this year like last? Whats the look of the new sensor after a short time in and the issue returning? If there residue building quickly, id look into the crankcase vent system and maybe even do a compression and leak down tests.

Chpthrill, the sensor never shows any ‘fouling’ evidence. Infact if I just pull it out and let the dry air evaporate what substance may be on it, it’ll work just fine. Each time I’ve been home and taken it out to clean it, I also wipe down the inside of the intake manifold and clean the spark arrestor. I feel all these are good practices but still aren’t getting to the source thatvis truly causing the issue.

Basically, you’re saying to do a complete tune up; cap, wires, plugs and check the PCV system too. Those are all legit recommends. I’ll do those. Thanks!!


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[chpthril]

That intake is a dry setup, so technically there should not be any vapor/liquid in there to evaporate. Some residue is normal after a number of hours/miles, but once cleaned away, should not return in a short period.

[moore3]

Agreed. The initial wipe down last year did show some residue, as I may have been the first to perform a wipe down, since new. The repeat wipe downs have not resulted in a residue laden towel. Your suggested complete tune up is definitely cheaper and less time consuming than doing the injectors.


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[chpthril]

Yes, I would eliminate the maintenance items first.

[UNSTUCK]

This is interesting to me. Maps usually plug up and fail due to egr contaminate plugging them. I don’t believe you have egr. That eliminates pretty much everything you’re going after. Are you getting an engine light or code? I really wonder if your map issue is actually something else and taking the time to “fix” it is is temporarily fixing something else. Lose harness connector or bad wire in the connector perhaps? Either way you should get a check engine light.

[moore3]

Ended up being tune up ****. All new plugs & fuel filter did 95%of the repairs.


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[KoolAid]

Thank you for updating this! At least you got it fixed