badgerooster

Failed echeck with bad nox. Each test has gotten worse. I've got 5 years left until it is grandfathered in. $300 buys me 2 years of driving time until I get into it farther.

Two ways to approach this. Put money in to fix this. Hopefully.

Or put money into things that I'll need in future.

Car runs great. I've haven't put a ton of miles on it since I got it but seems fine. A couple of issues like temp while sitting still and low oil pressure at idle while sitting at a standstill.

I've cleaned up egr trying to get past nox but it got worse. I checked tbi injectors and they seem to have a nice cone but seemed like there was a little extra drips flying around.

It will cost me $80 to have it checked a certified station which goes towards the $300.

First time 3rd gen owner. I've got some vac testers, timing light and other harbour freight tools that father in law left me. But I really want to get this over with and plate it. I could deal with the $300 but really don't want to. It's better than jacking around chasing possible electronic and vaccuum issues.

Generally I guess I'm asking do I put money into things that qualify as echeck help and could be switched over to another engine or try to solve the problem and hope in 2 years I'm not going thru this again.

91 firebird convertible, 305, tbi, single cat, ohio echeck

xX89RSXx

iTrader: (1)

What did they say would cost $300 exactly? Is the cat original? Mine was and I failed terribly because it was falling apart internally.

What is your temp getting to and what does the oil pressure read?

Are plugs and wires new?

Try to run some seafoam through the intake to clean out the engine.

F-BIRD'88

Post the complete results from your smog tests.
High NOX is caused by a hot combustion.
Lean AFR in 1 or more cylinders, too much spark advance.
Lack of egr flow. Failed cat.

badgerooster

First test I do not have since it was with the prior owner. But I found out that if I had a 30% improvement it would be under and pass NOX. Previous owner said he did oil change, spark plug wires, and etc. Seems to make sense with what I see.

My first test I got
READING UNITS LIMIT RESULT
HC 79.7 PPM 114.0 PASS
CO 0.37 % 0.63 PASS
NO 1191.6 PPM 796 FAIL
CO2 N/A

I tried pressing in on egr and it seemed like it could have been stuck shut. Prior to second test I cleaned up egr valve. I put a new gasket on and reconnected it. I went to the auto parts store and had them bring one out (not the same but similar). It moved a little easier than mine but not by much after cleaning.

Second
READING UNITS LIMIT RESULT
HC 84.4 PPM 114.0 PASS
CO 0.34 % 0.63 PASS
NO 1314.7 PPM 796 FAIL
CO2 N/A

Car starts right up runs good. I went straight there the first time, the second I drove around. Running temp is pretty consistant a 175. Second time I drove around the temp would rise when sitting. It was a hotter day but I do believe it would be a problem in stop and go traffic. It got up to 220 pretty quickly.

One thing that does happen after running awhile is low oil pressure at idle. Low as in a waivering 5 (up and down) but mostly down. Would that be the oil pressure switch by the filter?

It seems to point to either an engine that is just worn out or an empty cat.

It costs $80 bucks for a service station to go thru everything. It goes towards the $300.

I found single cats online for about $140, egr $60 autozone. Thats $300. But in two years if the cat doesn't solve it I'm in the same boat.

I believe the egr is going to work like the new one did. From what I saw there was a electronic sensor that controled the vaccuum. Maybe it's that.

I know I could rack up money in O2 sensor, oil pressure switch and other upgrades. Would it be worth getting those new and leaving egr if it checks out?

The car sounds really good as far as rumble out of tailpipes. Single line back to muffler then dual out. Could that be because of empty cat?

badgerooster

Please read prior post with most info.

Sorry I didn't really answer your questions.

Startup oil pressure will be around 45 for a little then it usually stabilizes around 33. At idle it is around 7 consistant then after heating up it will drop to 5 and lower. It will kinda waiver at that point.

Previous owner supposedly put plugs and wires. His story seems to match with other things he said.

Sea foam? Heard of it. What does it do and is at Autozone or such store?

bcmag

take some timing out of it and itll pass i promise.a cat does almost nothing for nox.

badgerooster

Please read prior posts for most info.

I understand about the high nox. What would make the internal combustable temp more that engine running temp?

"Lean AFR in 1 or more cylinders, too much spark advance." F-bird

Good one. What? AFR? Sorry we picked up new vehicles about 8 years ago and I haven't had to pay attention to any of the electrical engine stuff or emissions. I've had 67-72 truck stuff before I got this firebird.

Saying that I do believe it runs lean or too good. How would you change spark advance. Distributor?

Sorry so long in responding my father in law passed away and my wife and I are dealing with that and extra.

Thanks for any help.

ASE doc

EGR is controlled by a vent solenoid. ECM allows EGR by closing vent, allowing ported vacuum to the EGR diaphram. Test the diphram using a vacuum pump. Engine should stall or stumble severely with vacuum applied to EGR diaphram at idle. If not, try lifting the diapram with your fingers. Does the egine stall or stumble? If not, clean passages. Also the EGR diaphram should hold vacuum, some bleed off after a few seconds but should still hold for 5 seconds. If not replace valve. NOx can be reduced significantly by retarding timing 3-4 degrees. Loosen distributor fixing bolt and turn distributor clockwise. Youll need to disconnect the timing connector first then clear codes when youre done. Oil pressure, how many miles on the motor? What weight of oil do you use? The pressure sending unit is located just below the distributor at the back of the engine. The switch by the filter is the fuel pump cut off switch. Test oil pressure using a mechanical gauge. Temp will go high at idle. Fans come on at 223f.

ASE doc

NOx is produced when combustion tempuratures exceed 2400f. EGR reduces combustion temp by injecting inert gas (exhaust is mostly CO2) into intake stream. Other factors that effect combustion temp are AFR (air/fuel ratio), spark plug heat range, fuel octane rating, ignition timing.

badgerooster

Could the vent solenoid be bad? I did press the egr while engine was running and it did stall and stumble. I checked lines for being plugged too.

I do have a timing light, never used it but have seen them used. Knowledge of which way I would go on tick marks I have is zero. I just haven't done it.

As far as the timing connector and clearing codes. What?

Oil pressure, 105,000 miles. I don't know what previous owner put in. It was done at a Lubestop so I would guess they went with recommended weight. I'm just using a Haynes manual so far to do any repairs. I've read there is a pressure sending unit near distributor but also read about a oil switch near oil filter.

I thought my fans came on earlier. I'll pay attention more in future. I have seen it on but didn't look at gauge.

I don't know if anything was done to this car. Everything except for radio wire for amp looks factory. The only thing that seems a little strange from my 25 years of GM products is it shifts fast. Almost like a quick shift. It is a convertible with my guess of 2.73 gears for whatever that is worth.

badgerooster

I tried posting reply and it kicked me out. So if this is a repeat, sorry. Thanks for the help by the way.

You do mean 240 F not 2400 right?

I believe it is too much gas and timing (beyond a possible empty cat). From my understanding of the egr and that complete system is that it goes on a recirculated system. So at normal operating temp this system will stay open.

It just seems to take off when it starts. I did look at fuel cones on tbi and they looked fine except for maybe a little extra wild drops flying around. If everything checks out replacing them would towards that $300 and would help in the future too.

badgerooster

I did take it for my official emissions checkup. O2 sensor is bad and so is the tps. He said the car is not even running of the ecm. I don't get that one. The timing needs turned back too.

I'm a hardheaded polock and I bought the parts instead of letting them do it. There cost installed was $270 and I bought them for $50. So I have spent $145 bucks towards my $300.

I was going to put the parts on and retard the timing to 6. That's what I have seen on here. I'll check my Haynes (which suck). Then unhook the battery to reset the ECM.

I did buy some seafoam. I bought a small can since all the gallon jugs were gone. I guess it must work. I was reading the instructions and it seems like you can put it in the car anywhere.

I did drive the car around last night and finally got thru the first tank of gas. I've gotten rid of the old gas and my oil pressure numbers have changed and idle has changed. I guess with the new parts and ECM reset it will change again.

Where would the best place to put it. oil? valve covers? Is this something I should do multiple times. From my understanding to lower my NOx I have to get it to the top of the piston, cylinder walls. I have a month left to do this. It's my last temp tag. I'll search a little.

F-BIRD'88

The CO and HC readings from your emissions tests are normal indication the motor is not running too rich or too lean or ignition fault. But the motor still may not be running in closed loop and or the spark advance may be excessive.
But most likely a non fuctional egr system either cause the egr valve is faulty or the ECM is not running in closed loop ( faulty-lazy 02sensor) allowing the EGR to function.

Normally the egr valve remains closed at idle. but...
You can verify the vacuum diaphram in the egr valve is functional by temp plugging the vacuum line directly to intake manifold vacuum at idle.
The motor will stumble at idle when egr is injected at idle.

Combustion temp in the cylinder has nothing to do with the temp you see on the water temp gauge. Fire is hot. when the fire gets too hot , too fast NOX is created. (chemical reaction) Slow the fire down and limit the peak fire temp. (egr injection and or less spark advance.)

You can check if the motor is running in closed loop by reading the voltage output off the 02 sensor wire as the motor is running. (using a DMM or AFR gauge).

When in closed loop, the voltage will hug .450MV. +/- or cycle high and low quickly.
indicates the comp is reading the 02 sensor and regulating the afr.

The CO and HC readings from your emissions tests are normal indicating the motor is not running too rich or too lean or a ignition fault. (but still may not be running in closed loop and or have too much spark advance)
Most likely non functional EGR system.

When in open loop the voltage will stay higher than .450MV. If you create a temp manifold vacuum leak (pull off a vacuum line) it will drop ( lean),, if you were to introduce fuel ( propane down the carb or air inlet the voltage on the 02 will raise ( rich).

If the 02 sensor is "lazy" the motor will often regulate on the lean side and that makes the NOX higher. If the 02 sensor is non functional the comp will not run in closed loop and the egr probabily won't function either. Again high(er) NOX in exhaust.

When you get it so it will run in closed loop mode, once warmed up, your gas mileage will improve and you'll be doing your part to keep the air clean.

CrAlt

He said he is running at 175deg... will the ECM let the motor go in to closed loop at such a low temp?

Would putting in 93 oct lower his combustion temp and thus lower the forming of NOX?