My 2.0 started stumbling lately and checked all of the usual suspects, including MPS leak down and seemed to be perfect. After spending some time reading through various posting I found numerous references to MPS diaphragm issues even though they tested ok, so I opened mine and found that the diaphragm was indeed cracked.

I have 2 1.7 MPS which also test OK, so I decided to open them to see if I could salvage their diaphragm, but just like the 2.0, they were both cracked even though they tested ok.

What confused me is that all 3 had the spacer intended for 2.0s. The 2.0 was a 037 and both 1.7s were 049s and all had rivets intact so they had not been opened.

I measure the thickness of all 3 at 0.024, and a picture is shown below. Do I have it correct, is this the spacer intended to provide more latitude for adjustment in 2.0s? Any idea why they would have been in 049s?

I guess the issue with testing Ok, but still being cracked makes buying a used MPS that states "holds vacuum" risky. Being 50 years old, we should probably assume that used one will need to be rebuilt.

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Maybe Jeff B will chime in on spacers. Get one of Tangerine Racing repair kits

Dunno...an 049 with a spacer is something I have not seen. Seen too many MPS that 'hold vacuum' or pass the 'mouth suck test' that have a cracked diaphragm or otherwise leak.

The human mouth cannot suck strongly enough for a sufficient MPS test.

Well I guess I'm lucky because I have 2 049s with rivets intact and both had spacers - see below.

I've already ordered the Tangerine replacement and tuning kit. I'm also trying to decide which AFR gauge to buy because I will need to tune for a 2056.

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You never met my college girlfriend

Innovate Wideband. For D-jet I don't think you'd need a bung.

Oof, I am not a fan of Innovate. I installed an LC-2 on my 914 last winter and I've killed two 4.9 O2 sensors in only around 4,000 miles. and my experience is not unique.

There are a lot better options out there, such as the AFR500v2.

If you're using data acq and don't need a display then I'm a big fan of the 14Point7 Spartan 2. Using that in the race cars and quite pleased.

Greg speaks the truth-my experiences exactly with all products (plus the LC1 sucks too).

I've looked at the various AFR gauges and Innovate did have a lot of negative reviews, primarily due to premature sensor failure.

I also read each of their installation manual and 14Point7 gives very detailed instructions about placement of sensor to both ensure accuracy and protect the sensor from moisture and other adverse conditions. I have to wonder whether Innovate would score better if they took the same precautions.

Don't they all essentially use the same Bosch sensor?

Thanks for all the input!

Yes, the same basic sensor, if not the identical one. The 4.9 in the Innovate and Spartan were the same exact Bosch sensor (mounted in the same location). So it's all about how the controller manages it.

It's been quite a few years since I had the predecessor to the AFR500v2 ("NTK"?) but that was a 4.2 NGK sensor and I had good service with that, too. As far as I know, the subsequent race car owner is still using it some 10 years after I installed it.

i think the sensor is the same, i have had my AFT from Innovative in my car for 5 years i think? maybe longer, whenever i bought my Triad exhaust, might be closer to 8 years now, no issues.

Phil.

I believe the 14point7 controller's O2 sensor heater control PID loops are tuned better than those in the Innovate resulting in less thermal cycling and longer life. It's also possible the resistance measurement is more accurate, again leading to better control. Not sure if either use the driver chip Bosch natively does.

Some over brands use different components. The NTK L1H1 sensors in particular are a bit more robust than the LSU4.2/4.9 in my experience and come recommended by a number of higher end ECU companies with built in controllers. More expensive and a little harder to come by than the Bosch LSU which is why I think most of the aftermarket avoids them.

Which side does the spacer go? On the side closer to the adjustment screw, or the other side?

I like the Autometer Wideband AFR.

Have on on the teener and have had one on the Harley for MANY years now without a problem.

Between the diaphragm and the part load stop. The idea is to allow greater movement before the diaphragm hits the part load stop.

Great, that's what I thought. Thanks!