Hey folks. Hope this isn’t a known / stupid question, but I’d like to replace my OEM map sensor with a new OEM sensor (part #: 37830-PAA-S00), in my ‘98 Civic EX (d16y8). The online dealerships I’ve used for OEM parts want $115 for it plus shipping, but they’re all over eBay for anywhere from $30-$60. I’m wondering if anyone has used these. They appear to be genuine OEM sensors, and the description also states they’re OEM, but I’m not confident they will be genuine OEM parts. Thoughts?

 

Link? Usually it's fairly easy to spot fakes as long as you're >0% internet savvy.

Any particular reason you believe you need to replace yours? They're pretty dead nuts reliable and not really a maintenance item at all.

 

here’s an example:
https://www.ebay.com/itm/186667772927

I’ve got an ongoing stumble issue at partial throttle. I’ve replaced many components, as I figured they were due after 200k miles anyway ( while retaining the original parts) I’m fairly confident the issue is a dirty / stuck injector, as I’m seeing persistent STFT & LTFT pulling fuel when the issue occurs. I do not believe the problem is the map sensor with, but I figured I’d buy one just in case, and I’ve noticed a lot of the OEM parts for this vehicle are becoming harder to get, discontinued, etc..


ETA: I have no check engine light, a bit surprising, given the constant hesitation / stumble issues. I’ve replaced fuel pump (OEM, fuel filter (man that sucker was nasty). Cap and rotor, plugs, wires, coil are all within less than 20k miles. I checked my cat, expecting it to be clogged, or look like it was starting to break down, and it looks like it just rolled off the showroom floor. Also replaced the fuel pressure regulator. I have a manual gauge on it, and it seems within spec, but it’s underhood, so I can’t see it while driving. Idle pressure is around 32-35psi (with vacuum line attached). Probably a few other things I’ve done, but don’t recall at the moment. The issue has been going on for some time, but has recently gotten much worse.

 

That's fair. I'd check the wiring for the MAP very carefully. It has its own fully dedicated circuit, i.e. the 5V sensor supply runs to the sensor unshared and the sensor ground back to the ecu unshared (and both uncut on an OBD2 car), so it's totally plausible that you could have a MAP wire issue that doesn't show itself anywhere else. Are you looking at OBD2 data, or is this via a Hondata S300 or other rtp board? What chassis are we talking about here?

I think that listing looks pretty legit, especially after looking through their other listings real quick. I've had pretty good luck with buying OEM parts (especially domestically discontinued ones) from eBay stores like this one. Most of the parts I needed to rebuild my steering rack recently were unavailable in the states and this is exactly how I sourced them. You might apply some due diligence and spend some time reading through the buyer feedback to double check, seems like a worthy investment to avoid throwing $30 in the trash.

 

thanks man, appreciate the feedback. Yeah, I’m just getting the data from my BlueDriver scanner. It does ok, but I’m sure I could get much better data from the s300. I haven’t installed that yet. lol. Another case of buying it before they disappear.. so that’s sitting in a box, waiting… I wanted to get this running better before throwing anything else into the mix, like a tune. Especially since I have no clue what I’m doing with tuning yet. I guess it’s got a z6 baseline tune on it, which should get her running, but apparently the timing tables are different? So I’ll need to figure that out when I hook up the s300.

I thought the seller looked pretty legit as well. No weird misspelling of things and stuff like that. I didn’t spend much time investigating the feedback yet, but will. I noticed they’re only at 95% positive, so that should be a lot better to be honest, but I’ll read up before buying, to see what that’s about.

 

I did get the refreshed injectors in today, and she seems to be running much better. Will have to see after a few more drives, but so far much improved. These things were absolutely terrible.

 

Well, replaced Injectors with OEM “flow matched” set from a reputable seller. That seemed to help, but then I went back to severe hesitation. Still no CEL.

So today I swapped the fuel pump and filter, and the issue persists. I’m at a loss with this problem. It’s so bad now I’m not comfortable driving the car, and my normal daily needs a transmission (‘03 Yukon). Reaching the end of my rope. I don’t know what else to do. Practically all ignition and fueling components have been replaced at this point.

 

When you say severe hesitation, what symptoms are you experiencing?

 

it will be fine sometimes, with plenty of power, and then under load, it will just have no power at all. It idles fine, no issues whatsoever, but under load it (not always, but sometimes) will feel like it has less than half power. Then it will surge forward, if I keep foot on the same point on the accelerator. STFT and O2 readings will show -15-30% when this happens, so I assumed it was fuel related. The O2 and STFT trims keep in line with each other. I do have an exhaust leak, just haven’t wrapped up a few other things I need to do underneath, so haven’t fixed the exhaust leak yet. AFAIK, it’s only leaking after the header though. The header should be sealed well, but pre-cat does leak. I don’t think the difference between the 2 O2 sensors would cause such a problem though, but I’m open to opinions.

 

I experienced an issue similar to what you have described with one of mine a few years ago... turned out to be a damaged cat. The cat medium was broken away from the body and would move around inside the assembly... when it turned sideways, no exhaust gas could get through, and this is when the performance was really weak. When it happened to "bounce" back into place, exhaust flow was nearly normal and the car felt fine. It couldn't hurt to check.

 

thank you for the tip. I unfortunately (or fortunately, given the cost of cats these days), already checked the cat and it seems to be showroom fresh. I was expecting some small amount of breakdown or clogging in it, but it really looks good, and seemed to flow well, just testing with a 6hp shop vac. I don’t know what else I can do to test it, but seems good.

 

As I’m running out of ideas, I was thinking this could be the TDC sensor, but looks like that’s part of the distributor. Also wondering about the crank position sensor.
Apparently, OEM dizzys are unobtanium, or $600+.. so looking at part store brands, might go with that. Hate to keep throwing money at this with the parts cannon, but I’m still not getting any CEL, and the problem is pretty severe, and I’m really hoping I’m not causing any further damage.
Anyone have thoughts on either the TDC sensor or crank position sensor..? If you think I should replace, any brand / retailer recommendations.? Oreilly has a Cardone reman unit and a WAI Global “New” one available.

 

It's almost funny... I ended up having a MAP sensor issue this week. Same symptoms you are having, with large negative fuel trims and intermittent stumbling/rough idling, I could see over the Hondata app that my MAP was inconsistent and suspiciously high at idle so I pulled out the laptop and grabbed a log. Sure enough, the MAP signal was really noisy under normal driving and all over the place. Turned out the contact in the MAP connector was a little loose and needed a little squeeze with a pair of pliers so it contacts the pin in the sensor better.

That's why I was asking if you were on an S300 or similar or looking at OBD2 data... unfortunately the old K-line data is too slow to really see something like this with your logger. Try jiggling the connector and the harness around the MAP connector with the engine off and your app connected. If you can get the MAP value to jump around, you've found your issue. Here's what that looked like on mine, note everything else is zero but the MAP jumps from atmospheric to nonsense when I jiggle the wires:

 

Many thanks for your feedback. I actually disconnected the MAP last night, and planned to drive without it to see how it would do. However, after unplugging it, the idle went immediately to ****, and the CEL illuminated. I will look more carefully at it, and try moving things around while logging, to determine if I see anything jumping around.

 

You won't be running the engine without the MAP sensor, the ecu has no way of knowing how much fuel or spark to apply.

 

Logged with engine at idle, and moved / jiggled all the wiring around, pressing in the MAP connection, no significant change in the MAP reading. It reported between 8.3-8.9.

 

Good morning Honda-tech. I wanted to follow up, and report the issue we found with a good scanner, that showed a lot more data.
We found the TPS was reporting a negative value while at idle, and obviously this was suspicious.
unplugged the TPS, and test drove the car.. all fuel trims, O2 sensor readings were stable, nothing fluctuating as it was doing before. So all the problems I was having were due to the ECM thinking the throttle was all over the place, causing the hesitation, by cutting fuel.
I’m really happy that we found it!
Replacement TPS is on order, so I’ll deal with the CEL for a couple days until I can swap it out.
Unfortunately, I couldn’t find an OEM sensor, so throwing the dice with a Dorman part.

 

Nice, hope that fixes the issue

 

Well, that was a bust. I thought I had fixed the issue. Car ran great for a short time, and now it’s back to pulling large amounts of fuel while under load. I’m getting really frustrated. Need some ideas for what else this could be. The only other things I can think that may cause this is a bad ECU, or maybe the crank position sensor. If it were the crank sensor, I’d expect that to cause starting issues, but it starts and idles fine, just like it always has.
any ideas are more than welcome.

 

Still trying to resolve my issue. Currently, it’s running lean. Brand new plugs after about 5 miles end up with white electrode. And of course not running well. Any idea why the timing advance would be all the way at 30°, driving 55 at 2500 rpm..?