Sluggish Acceleration when Cold

[CJ_Boxster]

Hey Fella's and Fellet's

Ok after recieving my Boxster from the bodyshop, I immediatly noticed that the acceleration was lacking BIG TIME. So i figure since it wasnt drivin in 1 month I filled the tank up with gas and drove it abit and that seemed to clear up the low-mid RPM lack in power... However, the High RPMs (5k & Up) power curve seems to flat line.

Usually when that happens, I clean the MAF and problem solved but this time it didnt work, I also cleaned the airfilter and no change.

Yesterday morning I did notice that when the engine is cold, the mid-high rpm acceleration is non-existant until the engine warms up for about 30 seconds later, then the low - mid RPM power is there again... but still no power past 5k RPM's.

Anyone have any insite with this issue?


1997 2.5ltr 5-speed manual trans.

[Gary in BR]

Man, that sucks.

I dont know the answer but I wanted to bump you so people can help.

[CJ_Boxster]

Thanks Gary.

[turbo23dog]

Whenever I have these types of issues, I try fuel additives.

A magic mix that seems to work for me is a bottle of Techron Fuel System Cleaner and a bottle of Heet (gas drier) at the same time into a full tank of gas.

YMMV.

[CJ_Boxster]

I might try the Heet stuff cause i know it rained afew days while they had the boxster AND when i picked it up it was running below Empty so my first thought was trash/debris or moister/water jamming the fuel filter.

[dcporsche99]

Hey CJ,

...why was your car at the bodyshop?? I guess I missed that thread. Glad to hear you have 'er back.

IMHO, from what you described with the gas gauge having been below "EMPTY"....I'm thinking possibly fuel filter also. I take it you didn't get a CEL?? Or any new sounds??? Hmmm??? Hopefully, that's all it is.

(RE: Regarding poor power,..... I recently have an issue with a misfire on one of my cylinders that gave me a ticking sound (re: sticky lifter), poor power on the low end and a CEL ...I'm currently awaiting the parts for my home fix).

But, I will have to defer to the more experienced wrenches online regarding your issue...

Keep us posted!

[CJ_Boxster]

It was in the bodyshop getting repainted cause someone egged the entire car. Shes even better than before now.

UPDATE: Yesterday, i went home and pulled out the super expensive OBDII scanner my father has and decided to check realtime engine running data and right away 1 thing stuck out the most... On a nite where its 53 degrees the MAF airtemp sensor was returning a value of 113 degrees.

Then just for good measure since i didnt have any pcodes appearing, i told the scanner to show me the most recent previous pcodes triggered that arent current issues but past issues and i had "threshold rich cylindars 4-6 and 1-3" pcodes so that made it alittle more obvious that the MAF was causing the computer to dump loads of fuel into the cylinders at high RPMs because it thinks the air is so hot.

So unplugged the MAF and all the torq is back.. now to buy a new one.

[Dr. Kill]

Glad you found your problem - and that it isn't all that bad.

[Lil bastard]

I think it's time to replace the MAF. Aside from the Hot Film type Mass Air Flow Sensor, this part has the Intake Air Temperature sensor integrated into it.

You cannot fix this Intake Air Temperature sensor by cleaning the MAF. If it is wrong, all you can do is replace it.

You can test the Intake Air Temp sensor, which is really just a 'thermister' - it changes it's resistance to a constant electrical current based on temperature.

Remove the MAF and connect an Ohmmeter to pins 1 & 3. You should be seeing 2.3-2.7 kΩ @ 20°C (68°F). Any other value and the MAF must be replaced.

BTW, a high Intake Air Temp would cause the DME to lean out the fuel supply, not enrich it because Hot air is less dense than cool air. Seeing less air mass, the DME would reduce (not increase) the amount of fuel supplied.

[CJ_Boxster]

Originally Posted by Lil bastard

I think it's time to replace the MAF. Aside from the Hot Film type Mass Air Flow Sensor, this part has the Intake Air Temperature sensor integrated into it.

You cannot fix this Intake Air Temperature sensor by cleaning the MAF. If it is wrong, all you can do is replace it.

You can test the Intake Air Temp sensor, which is really just a 'thermister' - it changes it's resistance to a constant electrical current based on temperature.

Remove the MAF and connect an Ohmmeter to pins 1 & 3. You should be seeing 2.3-2.7 kΩ @ 20°C (68°F). Any other value and the MAF must be replaced.

BTW, a high Intake Air Temp would cause the DME to lean out the fuel supply, not enrich it because Hot air is less dense than cool air. Seeing less air mass, the DME would reduce (not increase) the amount of fuel supplied.

Well that makes sense. Im just glad the torq is back cause Chevron across the street is at 3.99 for super and with the MAF plugged in, the boxster was just ********************t*ng gas like a greengo after eating his first enchilada. Thanks for the data for the Ohm meter, I've wanted to check it but didnt know what values i should be looking for. Ill have to get some batteries for the Ohm meter before i can do that.

[Brucelee]

Originally Posted by CJ_Boxster

Well that makes sense. Im just glad the torq is back cause Chevron across the street is at 3.99 for super and with the MAF plugged in, the boxster was just ********************t*ng gas like a greengo after eating his first enchilada. Thanks for the data for the Ohm meter, I've wanted to check it but didnt know what values i should be looking for. Ill have to get some batteries for the Ohm meter before i can do that.

I always throw a bottle of techron on my car for issues like this. Seems to do the trick.

How are the plugs, old?

[CJ_Boxster]

well the plugs were replaced by me about 1 year in a half ago & 33k miles ago.

Whats the service interval for replacing sparkplugs?

[Brucelee]

Originally Posted by CJ_Boxster

well the plugs were replaced by me about 1 year in a half ago & 33k miles ago.

Whats the service interval for replacing sparkplugs?

Check your manual. It used to be 30K but I don't know about your specific vehicle.

[CJ_Boxster]

Yeah, Ill have to check. but i probably dont need to check cause im sure they are ready for a changin... I do have this tool that hooks up to a air compressor and is filled with a fine sand, I stick the sparkplug into this hole and pull the trigger and it sandblasts the sparkplug back to new looking condition.... I might use that since it's worked on my other TT cars it the past.

[Dr. Kill]

Originally Posted by CJ_Boxster

Yeah, Ill have to check. but i probably dont need to check cause im sure they are ready for a changin... I do have this tool that hooks up to a air compressor and is filled with a fine sand, I stick the sparkplug into this hole and pull the trigger and it sandblasts the sparkplug back to new looking condition.... I might use that since it's worked on my other TT cars it the past.

That's interesting. How much does a tool like that cost, and how many spark plugs do you have to restore to break even?

[CJ_Boxster]

Originally Posted by Dr. Kill

That's interesting. How much does a tool like that cost, and how many spark plugs do you have to restore to break even?

Heres one for 16 bucks http://www.importermall.com/Tool_Wholesaler/_Air-Spark-Plug-Cleaner_Sand-Blaster_Air-Tools_S11-air-spc.htm

Looks like the same one on eBay for 22 bucks 9 for shipping http://cgi.ebay.com/NEW-SPARK-PLUG-SANDBLASTER-automotive-tools-spark-plugs_W0QQitemZ4451842199QQihZ017QQcategoryZ43570Q QcmdZViewItemQQ_trksidZp1742.m153.l1262

so looks like it would pay for itself on its first use.

Mine essentially looks the same except mine is made by either Mac Tools or Craftsmen and look alittle more robust/professional grade... Also mine has a different air hose fitting than the ones shown in the ads i posted.

[Dr. Kill]

Originally Posted by CJ_Boxster

Heres one for 16 bucks http://www.importermall.com/Tool_Wholesaler/_Air-Spark-Plug-Cleaner_Sand-Blaster_Air-Tools_S11-air-spc.htm

Looks like the same one on eBay for 22 bucks 9 for shipping http://cgi.ebay.com/NEW-SPARK-PLUG-SANDBLASTER-automotive-tools-spark-plugs_W0QQitemZ4451842199QQihZ017QQcategoryZ43570Q QcmdZViewItemQQ_trksidZp1742.m153.l1262

so looks like it would pay for itself on its first use.

Mine essentially looks the same except mine is made by either Mac Tools or Craftsmen and look alittle more robust/professional grade... Also mine has a different air hose fitting than the ones shown in the ads i posted.

Cool - thanks for the link.

[Lil bastard]

Yea, those sandblasters are old school. But, you have to be VERY careful to make CERTAIN that there is no sand or blast media residue left on the plugs.

Getting that kind of grit accidentally into a cylinder makes buying new Spark Plugs weekly seem cheap!

[dcporsche99]

Hey CJ,

Glad it was a simple fix!

BTW, love that new tool link! Thanks for the info!

[Cloudsurfer]

Given how cheap plugs are, and how infrequently you change them, in the grand scheme of things I wouldn't remotely consider blast cleaning them. In the piston aviation world, where many run what are called "fine wire" plugs that are $80-$100 a piece, yes, you "service" (clean) those. In a car where the plugs last 30k are are less than $10 a piece, why bother? The risk of getting grit into a cylinder is very real.

Patrick