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.

The Bosch 2.2/2.4 and Regina fuel pressure regulators are different animals: make sure you got the correct unit that fits your application.
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See the 700/900 FAQ under 'Select Link' button on the top right.

Hiya steve. I have one of each at my disposal, and they both read exactly the same pressure at idle (~34PSI), at with the vacuum line disconnected (~42PSI). Seems people were right, the FPRs appear to be the same.

I'm going to try a bunch of different things come this Wednesday, even though my inspection is already expired. I've been parking off the street so I should be fine.

Things on my list are:
Inspect vacuum leaks everywhere
Clean throttle body
Clean intake manifold
Check flame trap and breather hose
Compression test cylinders

Also considering trying the 'water cleaning' procedure in the FAQ.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

The pressure readings are the same... I am disappointed. I swapped it back in, and there was really not much change.

My new (failed) emission readings are:

HC: 0.97
CO: 12.79
NOx: 1.36

Argh. Going to hunt around for vacuum leaks, maybe yank the throttle body off and clean it as well as what I can reach of the intake manifold.

The cat was replaced May 2003, so unless it went bad in about a year, I don't see that as being the cause.

Also, no OBD codes are present other than the chronic 3-2-1 cold start valve that doesn't mean anything.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

Sounds like running rich to cause high HC/CO readings. If not fuel pump, perhaps injector problem? You may want to disconnect the O2 sensor from the ECU and take a VM reading at the 02 while the engine is running. This could help validate a rich running condition. .01 = lean .09 = rich

Also, check/clean the PCV system including the breather box, and if this vehicle has EGR that could be a contributor.
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dnvolvo 89 765T 200k - 91 245 100k

Hiya, thanks for the suggestions. As I mentioned, I have a fuel pressure gauge and the reading is steady at roughly 34PSI on idle, and rises when throttle is applied.

I suppose it could be a leaky injector though? That would be unfortunate. But you would think that if it were actually running rich, the OBD should throw a check engine code at me for running rich, wouldn't it?

Anyway, I'll check the PCV, flametrap, etc. but how would that cause an emission problem?

And nope, no EGR!

I'm going to compression test the cylinders first chance.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

Hmmm...fuel pressure should drop significantly at idle...36psi is ok with FPR vacuum disconnected but should drop to 20 or so with vacuum line disconnected. A torn or leaky diaphragm in the FPR will give you extremely high emissions readings AND no change in fuel pressure at idle w/without the vacuum line hooked up.

FWIW I had a similar problem on my 87 900T saab...I replaced the cat two years ago and had the same problem this year....another new cat and the problem is solved again...this time I carefully saved the 5yr/50K warranty on the new cat for the next time!! Unless you replaced the cat two years ago with a genuine volvo cat, I wouldn't trust an aftermarket cat as far as I could throw it by it's tail!

Hmmm...fuel pressure should drop significantly at idle...36psi is ok with FPR vacuum disconnected but should drop to 20 or so with vacuum line disconnected.


34 psi at idle is fine.

Should rise to 43.5 with vac hose off and plugger.

With atmospher (no vacuum) on FPR, it's like WOT, so pressure goes UP about 9 psi.

B230 FP should never go to 20 psi.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Fuel pressure reads about 34PSI @ idle, goes up a bit when revving

Ken, I'll quote the Regina FI greenbook and let you draw your own conclusions (I have trouble getting my head around Kilopascals & such). [my words in brackets]

[Prior to FPR check, pump is jumpered and pressure checked for 43.5 psi. This is with engine off -- atmosphere (i.e., simulated WOT) on FPR diaphragm. Pump still running on jumper wire...]


Checking the pressure regulator
— Connect a vacuum pump to the regulator
— Pump the air out of the regulator [no specific vacuum amount given]

Check that the drop in system pressure matches the drop
in pressure in the regulator. [kPa, HG, psi??? this confuses me]

300kPa (43.5 psi) — negative pressure = system pressure

— Disconnect the hose from the vacuum pump.
System pressure should return to 300l kPa.

[Anyhow, your 34 psi at idle sounds like Bentley's LH 2.4 criteria -- about 9 psi below the WOT 43.5 psi]



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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Bruce, thanks for the info. You're right, it is a bit confusing. Also, I think those manuals have been known to be wrong before, so I guess the only real way to find out is to swap the old FPR back in and see what the readings are. I have a feeling this stuff my mechanic gave me to run through the car isn't really going to do a helluva lot to help me pass so it's going to come down to me swapping the Regina FPR back in. Thank god I didn't throw it away or something.

I have no idea what I would do if I didn't pass again even with the old FPR. I don't have a lot of $$ to go dumping into the car just to pass emissions, argh.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

How many miles on this car ?
Is the engine clean on inside ?
How's the flame trap, or the pcv ?
Is the car nice and hot when you go to inspection ?
I would run it for 20 minutes at high RPMs, prior.
(The Italian tune up.....)

p.s. Put a can of dry gas into the tank.

Ivan, the car has about 160K miles on it. The engine, as far as I know, has always been clean on the inside, at least the last few times I looked inside the crankcase, things looked clean. Will be checking the flame trap and breather system in a few days. The car is very warmed up prior to arriving at the inspection station having just travelled on the highway for a good 15-20 minutes. I'll look into the dry gas thing.

Thanks for the suggestions.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'