Community Forums:

I posted this in another thread but thought I'd make a new thread about it and see if someone else has any suggestions.

You know, it's interesting you're posting about this. Today, my 1990 740 w/regina failed emissions, 4 times. Both the HC and CO emissions were extremely high compared to the reading I had from exactly 1 year ago. The only things I changed that could affect the engine running between then and now are my spark plugs (went from NGK Platinum to Bosch copper) and my FPR (went from the stock Volvo Regina FPR to a $45 Bosch one from FCPGRoton), and my IAC (I bought an actual Regina Volvo IAC so that's NOT the problem.)

My mechanic thought it was the O2 sensor and/or spark plugs initially, so those were replaced immediately. When we ran it again after replacing the parts and doing a quick and dirty 'fix' by spraying carb spray in the vacuum, the HC and CO levels had dropped a very tiny bit, but still not enough to pass.

My original Regina FPR didn't have any problems, other than that I thought it could have possibly been the cause of hesitation. But that didn't seem to be the case. I have a fuel pressure gauge in the line, and I seem to recall that the new Bosch FPR has caused the gauge to read higher than the Regina.

Luckily, I have the old regina FPR still here, and tomorrow morning, after I run through a tank of this stuff that my mechanic ordered for me to help pass emissions, if I fail again, I'm yanking the FPR (making note of the PSI reading from the Bosch during idle and revving) and then putting the old Regina one back in and comparing.

In case anyone's curious, the readings of my emissions for July 2004 was as follows:
HC: 0.42
CO: 4.8
NOx: 0.64

This year, it's off the charts:
HC: 1.21
CO: 15.80
NOx: 1.49

Passing is:
HC: 0.80
CO: 15.0
NOx: 2.00

So tomorrow afternoon, I'll post a follow up my thread.