Values rise after catalytic convertor

P

poorboy

New Member
Joined
May 6, 2004
Running bluetops and armstrong 93 chip or delco chip at 35 psi

Values before catalytic convertor:

At 40 km/h

HC limit 106 actual 151
CO limit 0.59 actual 1.27

At idle

HC limit 300 actual 208
CO limit 1.5 actual 1.71

NOx limit 1164 actual 435

Values after catalytic convertor

At 40 km/h

HC 277
CO 9.91

At idle

HC 288
CO 4.34

Nox 290

Why are the values increasing with the catalytic convertor? I have tried the factory cat and a fairly new aftermarket cat. I have also tried switching out the 02 sensors twice. Both brand new ACs, but I believe they are not getting over 800 mv.

Need help!
 
More info. The values increase dramatically at 30 km/h.

Engine temp is 225 at the beginning, rising to 250 by the end.

Factory cat has less than 24,000 kms, aftermarket less than 1,500 kms
 
Those readings look really rich. You're running a stock chip with a 36 lbs injector? Is the Reds93 made for 36 lbs injectors? If so, run the Reds chip and bump the FP to the Reds specification. If not, try getting a chip to match the injector. I suspect that the temps may be rising because of the excessiviely rich mixture. How old are the injectors? Are any of them leaking?
 
Red's chip is for bluetops. I don't think the injectors are leaking. They have less than 10,000 kms on them. Injectors are over 5 years old, maybe approaching 7.

Temp is high because I unplugged the cooling fan because of the 160 deg thrermostat. Tried running a higher FP, int sometimes goes down to 128, but BLM is 160
 
Fuel pressure guage also holds pressure for a long time after car is shut off, so I don't think the injectors are leaking.
 
Originally posted by poorboy
Temp is high because I unplugged the cooling fan because of the 160 deg thrermostat. Tried running a higher FP, int sometimes goes down to 128, but BLM is 160
Click to expand...
:eek:

Leave the cooling fan connected and find out why the BLMs are at 160. The Reds chips are pretty rich, but high blms indicate there is false air after the MAF. Possibly a vacuum leak. This will cause the computer to think lean and the injectors to open up and give it fuel (a lot of fuel at 160 BLM). Is the EGR valve leaking? Are you using a factory EGR? Are you using a factory PCV valve? Do you have intake leaks? Are there leaks in the flexible hose after the MAF? Are all the vacuum lines okay?
 
I'll reconnect the cooling fan. I am running the factory PCV with Pete Tomka's adapter.

I checked the GM EGR by pulling off the vacuum line and compressing it and then putting my finger on the end, and the diaphram stayed compressed.

Also running Tomka's cold air system. Hose was in good condition last time I checked as he provides good brackets.

Switched out MAF's and made no difference.

Old MAF 5g at idle 24g at 40 km/h

New MAF 5g at idle 12g at 40 km/h

Car ran 11.96 last year, so I thought it was in tune.

IAC and TPS have also been reset

Hairline crack in the driver's manifold, but I've heard of people passing with a large crack in it.
 
I don't think a hairline crack in the exhaust manifold will affect emissions too much, but if the crack is in the intake, then you'll have problems. Now, try blowing propane at the EGR valve. And anywhere else you might suspect there would be a vacuum leak. Are you running vacuum brakes or powermaster? If vacuum brakes, is the booster leaking?
 
Brake cleaner sprayed on EGR and all connections. Didn't seem to do anything. Engine did not speed up.

Fuel pressure levels have been tested at various pressures and values climb as fuel pressure climbs.

NOX is low, even though engine temp high.
 
Brake cleaner sprayed on EGR and all connections. Didn't seem to do anything. Engine did not speed up.

Fuel pressure levels have been tested at various pressures and values climb as fuel pressure climbs.

NOX is low, 86 even though engine temp high.

Two new Delco O2's tried, but not toggling very much. Going from 200 to 300 mv even though engine is in closed loop.

Also tried inducing false intake leaks by pulling a vacuum line.
No effect.

Running DeQuick intercooler.

Could ignition module be bad?
 
I'm really not so concerned about NOx results. I'm more concerned that you've encountered a unknown vacuum leak from somewhere. BLMs should be at or near 128. BLM is long term fuel trim and intergrator (INT) is short term fuel trim. INT will make minute adjustments, to keep BLMs in range. When INT runs out of adjustment, BLM cells adjust. A BLM of 160 means the cells have adjusted to maximum lean and fuel is being added to compensate for the excessive lean condition. You've asked about ignition issues. If the ignition misfires, then the O2 sensor sees an excessive amount of O2, because the mixture did not fire. This will cause the O2 sensor to think the mixture is lean and add more fuel (that on top of the fuel that is already not being fired). So this could also be an issue. But usually, the HC is through the roof and CO is on the floor. Lean misfire creates a lot of HC, because HC is unburned fuel and CO is partially burned fuel. In essence, the partially burned fuel will be almost none and since the fuel is not being burned, it goes out the tailpipe (as HC) through the exhaust valve. You haven't provided the O2 contents or the CO2 contents from the emissions equation (as this too may answer a lot).
 
Don't have those values because technican did not ask machine for them.

Also checked charcoal canister and it seems to be fine.

Will concentrate on intake leaks and double check the hoses.
 
The cracked exhaust manifold can and will suck in air and fool the O2 sensor into thinking the motor is lean. This is worst at idle, and less and less of a problem as the exhaust flow goes up. If you are using the blue top chip and have the fuel pressure set in the 40-45 psi range, and the idle blm is 160 but the 65 mph cruise blm is 125-135ish where it should be, then my bet is the exhaust leak (especially since you can't find a vacuum leak).
 
Carl is correct. If header has a crack, as the pulses flow past the crack, it actually sucks air in. Non turbo car wouldn't matter much. This crack is pre turbo and pre 02 sensor.
 
The crack is a hairline and can only be seen if you look from the inside out shining a light on it from the other side. I've heard of lots of cars passing with cracks much larger than this one.

My emissions get worse as speed increases past 30 km/h.

I retested using propane looking for vacuum leaks, and did not seem to find one. RPM does not race. As well, I tried the cruise control on the car and it held steady.

o2 command side drops to 1V and stays there at idle. o2 cross counts fall to zero and stay at 0.2mv when taken off idle. o2 is not toggling. Tried 2 new Delco o2's and it produces same effect.

Under load in park, car seems like it is missing at 35# fuel pressure.

All other data in order except o2.

Another notable thing is that may be related is the car does not behave properly above 2000 rpm with all types of scantools hooked up to the ALDL. Tried OTC 2000, Snap On and Tech 1. All produce the same problem.
 
If the O2 voltage is 1 at idle and 0.2 off-idle, then it's rich at idle and lean off idle. What is the loop status? Is it in closed loop? What kind of temps are you seeing? What kind of information is the scantool seeing when RPMs exceed 2000?
 
Closed loop, 165 deg water temp. RPMs go above 2000, BLM goes to 160 and INT also works its way up there.

o2 values do eventually toggle, but no where near the 200mv to 800mv range they should. Voltage also moves around, can't remember the exact range, but I think the midpoint is around .32

What other values are you looking for? MAF values are earlier in the thread. All other systems seem to be operating normally.
 
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