2.7 throttle body loan

[Generallee]

Hi, anyone got a spare throttle body I can borrow for 2.7 986, 2001 model (manual). Macclesfield area. Still struggling on with my erratic idle when hot. Local specialist can't get me in for weeks... have changed lots but not made a difference. Had a chat with Porsche master tech and he suggested throttle body may be at fault and may not throw the MIL on. Will buy if cheap enough and guaranteed working. Getting to the end of my tether with this one - pretty sure there isn't an air leak - replaced plugs, coils, MAF,  air/oil separator, oil fill tube, filters.

Anyone any other ideas? When hot, idle goes from 300 to 900 rpm every 2 seconds or so. Fuel trim readings are mad, all over the place but oxy sensors reading reasonable, when running cold/warm everything reads normal.

Thanks

[edc]

2.7 and 3.2 throttle body all the same. 

[mavis.d]

I have a spare one if I can help

[That986]

21 hours ago, Generallee said:

Hi, anyone got a spare throttle body I can borrow for 2.7 986, 2001 model (manual). Macclesfield area. Still struggling on with my erratic idle when hot. Local specialist can't get me in for weeks... have changed lots but not made a difference. Had a chat with Porsche master tech and he suggested throttle body may be at fault and may not throw the MIL on. Will buy if cheap enough and guaranteed working. Getting to the end of my tether with this one - pretty sure there isn't an air leak - replaced plugs, coils, MAF,  air/oil separator, oil fill tube, filters.

Anyone any other ideas? When hot, idle goes from 300 to 900 rpm every 2 seconds or so. Fuel trim readings are mad, all over the place but oxy sensors reading reasonable, when running cold/warm everything reads normal.

Thanks

Easy thing to check is if all the clips at the top of the engine connecting everything are tight. Only take a small drag of air to make your idle flutter everywhere.

Have you actually cleaned the throttle body? If you have you will have had to re-calibrate it when you put it back on the car. Easy enough to do, turn on ignition till you get all the warning lights (don't start the car) and leave for a minute and you should hear the throttle body calibrating. After a minute turn it off, leave for about it 10 seconds then fire it up.

[Generallee]

Hi, thanks for all the replies. Yeah, cleaned throttle body, no difference, fitted second hand one today - still same. Pre-cat oxygen sensor showed stable at one point today whilst it was playing up, so ordered one of those... Bank 1 is drivers side, correct? Yep, calibrated, just same... Porsche master tech said he had only ever seen 1 throttle body go u/s but parts guys/breakers all say they sell loads! Anyway, it isn't that!

Been over everything again with carb cleaner looking for leaks.... weird thing though, when I load the engine up at idle with air con on, lights etc, it settles down, but still isn't right - does sound like an air leak, but why only when up to full temp, and the air leak must be massive as opening the oil filler doesn't even make that much difference...

[ooid]

Did you try with new MAF? 

[Menoporsche]

Are you absolutely sure MAF is for that car? Apparently there were various.

[ooid]

14 minutes ago, Menoporsche said:

Are you absolutely sure MAF is for that car? Apparently there were various.

Exactly. The bosch one in the europarts should calibrate properly. The OEM porsche brand of course over-priced not sure about its long-term use but there are some very cheap MAF for 986 and not all of them can work properly, especially on the early 2000's...

[Generallee]

Yes, correct MAF - same with both. Same fault even with MAF disconnected. Guy at 9 Apart Ltd said it may be the engine temp sensor. My scanner says the sensor is saying it is around 98 degrees when the fan kicks in, the dash says just over 80. The air inlet temp reads around 10 degrees higher than ambient too. 

If I put the air con and lights on when the idle is erratic, it does calm down but still isn't smooth - and then yesterday evening it was fine for an hour, then went out later and the fault was back.

Going to find someone to scan it today whatever happens....

[ooid]

hmm, final suggestion would be to book with nearest OPC diagnosis. They would charge 100-150 GBP max. but would give you a better idea of what actually wrong is (due to their computer info and previous experience in the book). You can then decide what to do. They are pretty sharp and good at diagnosing problems, just not appropriate and good value for fixing though!  

[edc]

If you are closing in on the coolant temp sensor/air inlet temp sensor then use an OBD tool to monitor the live readings. What often happens with these sensors is that when they go bad they give the same reading or a much narrower range and this has the effect of bad running at certain temps ie when you are hot. I've had this previously on another car, albeit not my Boxsters.

Does it smell of fuel? If so then the sensor is probably reading cold like a cold start and throwing in more fuel. This might tie back to your fuel trim readings.

[That986]

If opening the oil filler pipe makes no difference then see if you can get that checked out, they do crack and die.

[Generallee]

Hi, thanks again for all the suggestions. Can't seem to get anyone to scan it... Had a chat with a really good mechanic, but he is off on his hols tomorrow. He reckoned up stream O2 sensor. I suppose a couple of sensors won't break the bank - we discounted temp sensors as they read correct on my scanner. Done the oil filler pipes already. Opening the oil filler makes the engine rev up and there is a slight vacuum, which would suggest there isn't a breather leak... or it would rev up... Doesn't smell bad. ECU does alter timing all over the place and I did see one O2 sensor just read a constant 0.8v once whilst the idle was erratic... just got to get them out now - any tips?

[edc]

It's only the pre cat sensors that should make a big enough difference. If possible swap over to seeing the fault is still present. 

[Generallee]

I believe you can just unplug them, however lambda sensors are really a consumable and seeing as it cost less to replace them than get it code read (which I'm struggling to do), I have started to replace them. First one was a struggle but the second one came out easy  - just waiting for another sensor to arrive tomorrow. I had to destroy the sensors to get them out and the wires aren't long enough to swap bank 1 sensor for bank 2 in situ. By the way, you can get 30% off at Eurocarparts online by using code SAVE30 at checkout. Not sure there is much else I can change that is consumable or a known faulty item. See how it goes tomorrow.

[edc]

Normally the pre cat sensor will give a CEL if it is not working properly. 

[Generallee]

I had a chat with an Audi Master tech, and he said he was working on a V6 Golf, similar problems, showed nothing, no Mil etc, even O2 sensor readings weren't bad but couldn't work out what was wrong, he swaped the wiring to the sensors and all was well - he reckoned imbalance in sensors can cause problems. I don't like changing parts and guessing what is wrong, in fact I hate it but no where else to go at the mo.

[Generallee]

New oxygen sensors, still the same... hopefully got it going to a specialist next week... shame, it is a nice car....

[ooid]

On 9/8/2017 at 9:14 AM, Generallee said:

I had a chat with an Audi Master tech, and he said he was working on a V6 Golf, similar problems, showed nothing, no Mil etc, even O2 sensor readings weren't bad but couldn't work out what was wrong, he swaped the wiring to the sensors and all was well - he reckoned imbalance in sensors can cause problems. I don't like changing parts and guessing what is wrong, in fact I hate it but no where else to go at the mo.

Shame could not see this. I had V5 Golf 4 motion for over 17 years. Very different cars with 986, even though symptoms might look similar. I really think you do need a proper inspection with OPC but then decide your own DIY solution.  Could also be solenoid or switchable tappet?