Been looking into MAP harness issues this weekend and I'm not sure I know more or less than before.
I started with the new *704 connector pigtail. Turns out it's the same damn connector as on the car. Meaning that either 1) the sensor used for the APR k04 v3.1 file is different than the one used in the Golf R, 2) I was given the part# for the GTI not the R, or 3) VW doesn't give any fucks about how well their connectors fit in mass production. I ruled out #2 pretty quickly with a quick search. Now I need to check on #1.
So I installed the new pigtail for shits and giggles with some quick-connects, in the event that the old one on the car was messed up somehow (the pins could have been pushed back and too far recessed, more on that later). The new pigtail didn't work at all with the new sensor (constant overboosting at part throttle, no boost >7.5 PSI). It worked a little with the old sensor (not always overboosting at part throttle, sometimes initially getting >7.5 PSI but always reverting to 7.5 PSI). Yet as I took it off, the latch snapped off. It must've been sitting on the shelf for a long time because this connector is much more brittle than the connector that was in my car. So now the new pigtail is useless aside from a reference outside the engine bay.
Did some measurements on the bench to understand how it all fits together. The connector is 20 mm deep. The sensor body takes up about 18 mm of that space as far as I can press it. The pins in the sensor are about 16 mm from the far-end of the sensor body. All in all the sensor pins are inserted about 4.6mm into the connector, which might be enough to make good contact but may not be enough if the connector pins are pushed back into the connector housing.
That extra length on the calipers is how far in the pins should insert from the face of the connector housing.
In the meantime I fitted the existing connector with quick-connects and installed it into the car. Didn't work. I added some solder to the wires at the engine harness and re-installed the quick-connects. Didn't work. I bypassed the connector completely, installing gold-plated quick-connects directly to the pins of the sensor and into some quick-connects which are soldered into the harness. Doesn't work with the new sensor, but it does work with the old sensor. Until the car warms up, then the connection seems to be intermittent.
On the one hand, this is the best I can do to make a connection to the MAP sensor. On the other, this is not nearly the best solution for a connection problem to the MAP and it sure as hell isn't a long-term solution. So I'm going to continue to track down the right connector for this MAP. I can't settle for anything less than the quality of connection of the stock parts.
Yet as it stands today there's no way I can take this car on a 2500 mile road trip in this condition. It's not so bad that I can't drive it around town but I'm not risking having a broken down car in the middle of nowhere in Kentucky. This is super disappointing because I was hoping it'd be at least good enough to baby down to South Carolina, where my buddy, a lead mechanic at a VW dealer, can take a look (and get a taste of k04).
Sincerely, XGC75
Oh and lastly, this happened today:
Sincerely, XGC75
Pretty encouraging to see a tuned car that hits the track have this kind of mileage. Hopefully you can get your MAP issues fixed soon.Oh and lastly, this happened today:
Sincerely, XGC75
I have, yes. But the car passes the dipstick test (the car idles horribly with the crank case leak) and every time I touch the MAP connector the car behaves differently. As a philosophical matter, I just have to have the right part on the car anyhow. I suppose I'm just hopeful that putting the right connector in there is the fix I need. If not I'll end up addressing the PCV with a catch can.have you thought about the PCV? im only stg2 but I was surging violently before replacing it. now totally perfect.
THE CAR WORKS AGAIN.
Fuck.
I haven't looked under the hood to see the changes with my own eyes yet, but they did 5 things:
1) New intake manifold
2) New MAP sensor
3) Fixed the connector
4) Fixed vacuum lines to the N75
5) Replaced the water pump
Okay, not all are related to this issue. However, this is the time to throw a warm shout-out to Team VW/Audi in Merriville, IN. These guys are the shit. Not only can I walk in back and tool around with the techs, explain all the things I've done, take a few for an extended drive (literally 3: a tech, junior tech and master tech), hear and discuss the solutions and plan out the order of repairs with them, but they also got the intake manifold and the water pump covered under warranty for my 100k mile nearly 5-year old k04'd car. So I got all the above done for $410. Well worth it.
Let's take this piece-by piece.
The intake manifold actuator arm was broken. The actuator itself was okay and the arm itself was okay, but the shaft that goes into the interior of the IM and moves the flappers was moving into and out of the IM by about 1.5 cm. They typically move a bit but the master tech confirmed right away that it was bad. We sprayed some ether on the shaft and it didn't mess with the engine idle in either the "out" or "in" positions but the car struggled slightly when it was in the middle of travel. So this wasn't causing surging but it was doing 2 things: 1) letting unmetered air leave the system when going from vacuum to boost and accepting unmetered air when going from boost to vacuum; and 2) throwing off trims as a result. I bet this had everything to do with the kinda 'surge-y' unpredictable behavior during part-throttle acceleration around town.
The MAP sensor replacement threw me for a fucking loop. I'd replaced the damn thing 3 fucking times now. The first time was when I got the k04 installed and tuned to APR k04 v3.1 and the first sensor I bought didn't seem to work. I chaulked that up at the time to the harness not engaging fully. The second time was when this mess first started. That one never seemed to work. When I got a call from Marty (service manager - ask for him by name and tell him Trevor sent you!) the first time, he told me that the sensor in the car (call it the second sensor I bought) didn't pass their tests and the third sensor I bought (the one I butchered) did. Obviously they couldn't send me home with a sensor that doesn't latch the connector into place so they got another. Anyways fuck those sensors.
I haven't seen exactly what they did to the harness, but I hope they replaced the solder joints with VW service-approved crimp-on butts. We were talking about just wiring the sensor directly into the ECU but I'm not sure they even got to that point considering the MAP sensor in the car was faulty. I didn't see anything about the connectors or harness on the bill at any rate.
They mentioned that the vacuum lines to the N75 were kinked and that they'd take care of it. Personally I didn't think that would be the cause of the surging issues because (I believe) they're there to transmit pressure levels and they don't need to flow a whole lot. Therefore as long as the kink didn't completely block airflow it'd be okay. But hey, I won't complain that they fixed them. Certainly gives me one less thing to worry about.
Last is the water pump. Frankly I would have preferred it wasn't touched beacuse I (knock judiciously on wood) haven't had any issues with it in 100k miles and don't suppose I would have in the second half of the car's life. But hey, it was free work and if I have any problems I know who to call about it.
So that's that. I bet the initial issues with the car were indeed the MAP sensor. The second sensor clearly didn't engage with the stock harness properly. Things looked better for a few days when I replaced the N75 and took off and replaced the MAP connector. Not really sure why it was good there, but then the more I messed with the harness the worse it got. I can't say unfortunately whether it was those spade connectors not making a good connection or the MAP I had going schizo. I suppose I'll know once I see what they did with the harness. If it's untouched then it was surely the MAP sensor this whole time, though even the "good" sensor (the third I bought) didn't work in any of those configurations (except the last configuration which I didn't try).
A couple clarifications on my previous post after looking in the engine bay. First, it appears they didn't do anything to the harness. My harness works! That's a good feeling. Also they didn't clean up the vacuum lines. This agrees with the bill.
Another note about drivability. The intake manifold was causing the hesitations on acceleration. The hesitations came on so slowly and gradually I didn't really notice them. They were hard to characterize. If I recall correctly, whenever I went WOT I'd get a bunch of boost, then a split-second hesitation, then full boost again. It makes so much sense now that I think about it: That shaft in the IM was acting as a limited-travel "plug". When I was in vacuum it sealed inside the IM. when I was in boost it sealed outside the IM. When it transitioned, it wasn't sealed and I'd leak a bunch of air, hence the hesitation and the loss of boost. In fact, I bet the pressure wave was picked up by the MAP and triggered the DV. Now it's all smooth. No hesitation, just fluid boost and torque. Lovely.
A couple clarifications on my previous post after looking in the engine bay. First, it appears they didn't do anything to the harness. My harness works! That's a good feeling. Also they didn't clean up the vacuum lines. This agrees with the bill.
Another note about drivability. The intake manifold was causing the hesitations on acceleration. The hesitations came on so slowly and gradually I didn't really notice them. They were hard to characterize. If I recall correctly, whenever I went WOT I'd get a bunch of boost, then a split-second hesitation, then full boost again. It makes so much sense now that I think about it: That shaft in the IM was acting as a limited-travel "plug". When I was in vacuum it sealed inside the IM. when I was in boost it sealed outside the IM. When it transitioned, it wasn't sealed and I'd leak a bunch of air, hence the hesitation and the loss of boost. In fact, I bet the pressure wave was picked up by the MAP and triggered the DV. Now it's all smooth. No hesitation, just fluid boost and torque. Lovely.
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