Cold Start issues - 996T

[shantybeater]

Hi All,

You may have seen my thread recently on the SAI error code. Bit of background - since buying the car (4 months or so) cold start has always seemed a bit erratic/lumpy. As the weather got colder the symptoms got worse. After fixing the SAI the idling issues have most definitely increased further.

On start-up the car idles high, sounding a bit lumpy. Then when it tries to settle the car rocks and struggles to hold smooth, it sounds like its missing, infact it sounds like it will stall out (but never does). This continues for a good few minutes. If I drive the car it dips in revs and bucks on occasion, acceleration remains unsmooth for a minute or so of driving but as the coolant temp starts to rise the car settles and drives fine, smooth idle etc...

Once warm all symptoms dissipate and the car runs fine.

I have no CEL, no error codes logged. Does anyone have any suggestions on what could be causing this? MAF? coil packs? I have a Durametric, any ideas on what values I should try logging?

Thanks for any help
James

[shocks]

James

When were the coils or maf last looked at ?

I had a spurious CEL issue for a while that started manifesting itself as an SAI issue then had the following done :

DVs replaced (forge over the plastic bosch ones)
Coil packs replaced (had this done on major recently)
MAF replaced (same time as coils)

The order was a bit erratic after the SAI issues (DVs were the actual problem) - OPC had three cracks at chasing down the CEL then when due for major service had the Coils and MAF replaced never had an issue since.

I never had these issues at cold start but did have it during cold(ish) running. Though there was no consistency to the issues at the time. It could have easily have been either the MAF (voltage had minor fluctuations from norm when run on durametric) or simply coils beyond their useful life.

Hope this helps. Best is get a good indy to have it looked at - which is what I did, found OPC not so hot to trot on fixing it :-)

[steve singh]

Sure you haven't got an air leak anywhere?

[shantybeater]

Thanks for the replies,

Hi Shocks,

I have no history of coil or MAF replacement so they could be original, perhaps a worthy purchase! were coils upgraded to a 997 part number?

The SAI error code was due to a missing relay (and wrong amp fuse), I replaced these last week and the system now appears fully functional with no error codes resurfacing.

Steve - Not that I'm aware of, surely a leak would manifest itself hot or cold?

[shocks]

shantybeater said:

Thanks for the replies,

Hi Shocks,

I have no history of coil or MAF replacement so they could be original, perhaps a worthy purchase! were coils upgraded to a 997 part number?

The SAI error code was due to a missing relay (and wrong amp fuse), I replaced these last week and the system now appears fully functional with no error codes resurfacing.

Steve - Not that I'm aware of, surely a leak would manifest itself hot or cold?

If you were throwing up SAI issues there is still a chance there is a leak in the system as Steve says, thats where I ended up with DVs being replaced - these were leaking. But it was not the only or rather the source of issue. You can check this post :

SAI Troubleshooting

The first indy wanted to have engine out etc - which didn't fly with me as the SAI checked out ok once the DVs were replaced. So it can be an awkward thing to nail sometimes and you may get run around advice wise. Needless to say didn't go back to him and opted to travel further afield to a better one

I seemed to be clear for a while after the DV replacements, also cleaned the MAF at that point. around 6 months later I'd get the CEL coming on, when checking via durametric I was seeing issues with the MAF voltage - OPC had also checked it but wasn't seeing anything wrong cleared fault and tightened hoses etc.

Come time for Major service and I opted to replace MAF with new one as well as have Coil packs replaced. The indy I use (SP Autobahn) pointed out the MAF voltages again and agreed replacing MAF wouldn't hurt, coils were done as precaution as they hadn't been replaced.

What had me head scratching was the SAI issues first time round.

Months down the line no issues drives like a raped ape.

[shantybeater]

Thanks for the reply, will take a look. I'm plugged the car into Durametric this afternoon and logged a few sporadic misfires in several cylinders as the car idled on choke, when it attempted to settle in to a warm idle I logged 10+ misfires in the space of 20 secs in cylinders 1 & 4. Once the car is warm no more misfires occur. I am hoping this points to a cracked coilpack issue!

[Rockster]

shantybeater said:

Thanks for the reply, will take a look. I'm plugged the car into Durametric this afternoon and logged a few sporadic misfires in several cylinders as the car idled on choke, when it attempted to settle in to a warm idle I logged 10+ misfires in the space of 20 secs in cylinders 1 & 4. Once the car is warm no more misfires occur. I am hoping this points to a cracked coilpack issue!

Cracked coils is a serious possibility. Coil packs seem to give up the ghost quicker in more humid climates. Read about cracked coil packs causeing problems with UK Boxsters at far fewer miles than my 02 Boxster had on its original coils.

Same for the Turbo. My 03 is on its original coils and with over 106K miles on them and nary a misfire. Check that. Two times the engine has misfired. Once after being left parked uncovered in a hotel parking lot over a night of heavy rain and wind; the second time after being left parked on near the ocean and a heavy fog rolled in.

[Steviesam]

Any update?

[shantybeater]

Not yet, if I get a chance I'll be doing a bit of work on the car today.

[shantybeater]

Quick update - Cleaned MAF, removed Y pipe and Cleaned N75 with electrical cleaner. Also went at the throttle body although there was minimal dirt to be seen. I did see traces of oil in the Y pipe towards the F pipe, is this normal?

Unfortunately there was no change to the cold start, still lumpy and missing. I managed to see 0.8 bar on an empty carriageway this afternoon so ignore my previous comment.

Next up is coilpacks..

[shantybeater]

In an effort to keep the thread up to date I took the car out for a quick drive after work. Again a minute or so after start up as the warm idle tried to settle in the car began misfiring. I took a closer look at MAF readings which fluctuated constantly between 1.5 & 2.0v. This settled into a fairly constant 1.5v once warm at idle

Misfires showing:


I saw another 2 misfires in cylinder 6 over a period of 10 mins when fully up to temp, none on boost

Making up a shopping list of goodies to do along with the coilpacks (sparks, exhaust heatshields etc.)

Would anyone suggest replacing o2 Sensors whilst i'm in there or would that be overkill?

[shocks]

I'd do pre-cat o2s; your call if you do post as well. Also consider replacing the DV, I went to forge DVs as the OE Bosch ones are plastic and end up leaking.

Really up to you what you swap out here but you'll have the back end off for the heat shields / spark plugs etc might as well check the hoses to ICs, you don't need to change these unless you intend to do map / run higher boost then you start looking into ICs (Ken at Nineexcellence has packages you might want to look at once you cost this list up !)

[shantybeater]

Shocks thanks for the response. I've already spoken with Ken and 9E is on my list along with upgraded DV's,exhaust etc.. but other things (like a diamond ring) are higher up the priority list at the moment. As it stands I'll be happy to have her running healthy.