Anyone here running a pattern MAF on their GEMS P38 and how do you find it?

My third used OEM one has failed, and while it runs pretty well without it, its a pig to start, which left the wife stranded on the schoolrun this morning.

I've ordered yet another used one from ebay, but clearly these are all old and failing.

Pattern units for other cars have a very poor record for actually working properly, so i've generally avoided buying a pattern one for this, but maybe its time to have a look?

Just after going thru 4 pattern crank sensors on this car, i'm super wary!

In theory they shouldn’t run without a MAF. The engine should start, run up to 500 rpm and then stop.

Yeah I tried a cheap GEMS MAF - did not work properly.

Marshall8hp wrote:

In theory they shouldn’t run without a MAF. The engine should start, run up to 500 rpm and then stop.

With the (broken) MAF connected it starts and then immediately dies.

With the MAF unplugged, First turn it fires then stops, if you try again it cranks for ages and sort of half heartedly stumbles into life. Once it gets to idle speed it then runs and drives totally normally. On the road you actually wouldnt know at all that theres no MAF installed. It accellerates and drives as you would expect. Perhaps a little down on power if you floor it.

Did 20miles in it yesterday with no MAF, started and stopped it 2 or 3 times. Same thing every time.

The problem is that on that second attempt, you need to fettle the throttle just right. Not enough, or too much and it wont go. Which is what the missus ended up doing. I think it then ended up flooded.

I was in a meeting and said i'd be along in 30mins. In the mean time some mechanic stopped to help and managed to get it started with just the right amount of throttle.

Sloth wrote:

Yeah I tried a cheap GEMS MAF - did not work properly.

Yeah, and this is my fear... Whats the solution? these parts are all 20+ years old, and clearly are all reaching end of life. Buying more used ones isnt a solution.

A while back i intended to attempt a translation unit that will convert the signal from a Bosch MAF to GEMS, but the issue is to do that, i'd need either a known working GEMS MAF to datalog, or a dump of the MAF/Voltage table from the ECU. No-one seems to have the ECU table, and who knows if any 20 year old used MAF is actually accurate enough to build a proper model from.

I had a pattern one on my car, admittedly it was the second one as the first one \i tried worked for about a week, and it seemed fine. Looking at the readings from the Nanocom and it was pretty close to what it should be and the car drove fine. I then noticed that the Ascot had an original one on it so decided to swap them over. Checked both with the Nano and while the original was almost spot on what the readings should be, there was no difference in the way either car ran.

Aragorn wrote:

Sloth wrote:

Yeah I tried a cheap GEMS MAF - did not work properly.

Yeah, and this is my fear... Whats the solution? these parts are all 20+ years old, and clearly are all reaching end of life. Buying more used ones isnt a solution.

Unfortunately I don't have an answer for that one - my GEMS P38 wasn't long for the world and for other reasons I ended up replacing it with one that happened to be a Thor. And now its got an entirely different engine it altogether.