hi all my first post so take it easy on me.

i got a 986 1998 tiptronic with issues. most i can or have already addressed. i get maf error code and am waiting for a bosche maf to arrive. i have done various jobs on her such as replaced cylinder head gasket, and ims bearing and hf transmission pump.

there is still a problem with the transmission. error code 1770.

DTC 22 = P1770 Load signal from ECM Substitute Motronic value, fixed shift map (KFO)

Possible cause:
- Wiring
- Tiptronic control module to B+ (Open circuit/short circuit to ground, short circuit)
- ECM

symptoms are slipping while in gears and under load, long and often 'hard' gear change, and transmission gets quite hot to the point of smelling the oil.



the mechanic tends to think its the MAF and once replaced will fix the problem.

any thoughts and suggestions?

 

Give the new MAF a try. Install it carefully and correctly. Clear DTCs. Even if the CEL is not on this erases/resets fuel mapping and other learned stuff from the DME's memory. The DME will (probably) adapt quicker to the presence of the new MAF.

Be careful. There have been reports of MAFs bought online not being the same/genuine article. I have no direct experience because the only MAF purchase I made I made from a Porsche dealer parts counter.

Also, some early MY Boxsters required a DME firmware update to be compatible with replacement MAFs. If (big if) your car falls into this class of MYs the MAF may be the right part # but because your car's DME is out of date in this area the new right MAF may not work right.

Sincerely,

Macster.

 

Check the fluid level in the tranny ...

 

thanks for replys

yeah fluid level good and new as just done hydraulic pump.

i got the bosche MAF with correct part number so should be straight swap

i suppose m y question should be would the MAF cause this with the transmission?

 

It is possible.

A bad MAF can supply bad data that is used to determine load (a calculated value) and a goofy load value can upset any controller that relies upon this value for its processing. The transmission controller I think would be on this list, along with PSM and maybe even ABS.

The Tip fluid level is ok and the Tip fluid tight.

So, replace the MAF and erase the DTCs (to reset learned fueling/ignition/etc.) back to their defaults, then drive the car.

Just a caveat... the erase DTCs action may not reset the Tip controller's learned values so it could be that even if you do the above there might be some residual odd behavior.

As long as this behavior is not too odd, suggesting a deeper problem, more driving might be required to give the Tip controller time to replace whatever junk/trash data it got from the old/bad MAF with good data from the new MAF.

Sincerely,

Macster.

 

Check out my battery post. Tip should have the 94R battery. My codes stopped when I installed the 94R ... lower reference voltages will give you issues.


https://rennlist.com/forums/boxster-...t-battery.html

 

fitted MAF and replaced battery. still no joy im afraid. seems transmission gets way too hot and slips through gears.

i also noticed when Im coasting its like not in gear and when i accelerate the transmission slips then grabs

hard to describe i know.....

could it be torque converter?

 

Could be. I'm not that knowledgeable about Tip ills.

One possible explanation is there is an internal Tip fluid leak that allows high pressure fluid to leak into a low pressure area which of course will cause the Tip to act up. Bands and other mechanisms in the Tip that rely upon high pressure fluid will not work right and all sorts of symptoms can arise.

Any excessive slippage can certainly overheat the Tip fluid.

The techs tell me of encountering a bad Tip where the Tip oil pump had welded itself to the housing or the shaft maybe the converter -- to something of that I'm sure... -- and this ruins the Tip.

Absent an internal leak, if the fluid is too hot, thus the Tip is hot, overheated, this can account for the symptoms.

The Tip could be hot because the car's Tip fluid cooling system is compromised.

IIRC, the Tip has a Tip fluid radiator, heat exchanger, which is used to (obviously) keep the Tip fluid cool.

Are you sure the Tip fluid lines are ok to/from the cooler?

Yet another thing to check is that air flow into -- and out of -- is not compromised by some trash or a loose/misplaced panel.

Also, if this cooler has a fan be sure the fan works.

Sincerely,

Macster.

 

I think that you would benefit from contacting someone who actually has knowledge of these gearboxes and can diagnose your issues with you. I recommend that you give Erikson Industries a call and talk with either Nat or Scott. They are pretty much that only company that I know of that really specializes in these gearboxes here in the states, and certainly seem to be very knowledgable.

Good luck and I hope that you get this resolved. Their phone number is (800) 388-4418

I hope that this is helpful.

Erik Johnson
GBox LLC

 

That's the best advice.

Tips are complex transmissions but there are those out there that know them and can diagnosis the problem and advise an owner what to do.

In some cases, this being one, all I can offer, probably all anyone can offer (save an expert who probably will not have the time to inhabit these forums nor the desire to give away free advice) is just some ideas/suggestions to help the OP nibble around the edges.

It is good to keep in mind, the mind of people that seek help here, that these cars no matter how accurate the diagnosis is will not fix themselves. Someone somewhere has to get his hands dirty. Sometimes really really dirty.

Sincerely,

Macster.

 

thanks for the replies

i live in australaia by the way

ok an update

changed fluid and a noticeable improvement, just from 2nd to 3rd now takes far too long sometimes 5 seconds!!

 

Well, that's not acceptable. There have been a few cases when the Tip's behavior has improved with a fluid change that another fluid change, a 2nd one, can help further. The idea is the 2nd fluid change replaces even more of the old fluid.

Generally a Tip (automatic) fluid change has just a fraction (around half) of the transmission's fluid drained. The rest stays in the torque converter.

In some cases this can be drained too but not in many cases.

But in cases where it can't be drained a 2nd fluid change has nearly the same benefit.

Would I were I in your shoes do a 2nd fluid change? No.

What I would do is this with some bit of background. The Tip is a ZF transmission and these are quite common used in a number of other cars. As a result there are ZF (Tip) experts in just about every place there are a number of cars.

So my advice would be to seek one of these shops out and solicit advice as to what do you. If a 2nd fluid change is recommended, well at least you know.

If not you have a shop that will stop the wasting of money on a 2nd fluid change and with your permission then undertake a repair of your car's Tip.

As long as the transmission hasn't suffered housing damage, run out of fluid, or suffered some mechanical failure (torque converter breakage or what have you) these can be rebuilt and made as good as new.

Sincerely,

Macster.

 

thanks guys for the replies. im thinking i will have to replace would this

http://www.ebay.com.au/itm/PORSCHE-B...item5aea855869

fit to my 2.5l 1998?

 

A like for like Tip swap is the way to go if you decide to swap the existing Tip for another one.

About all I can add is to be aware of what "warranty" (really a return policy/exchange policy) the used Tip supplier has. This is in case you get the thing installed and find it is as sick (or sicker) than the Tip it replaced.

Have you priced a Tip rebuild? While this might be more expensive initially you know your Tip has never run out of oil or suffered any mechanical damage.

Generally you are better off rebuilding a Tip that you know the most about. It is the best starting point for a rebuild.

Sincerely,

Macster.