Emissions 2.0!!

[Cochip]

About a month back I posted a question in regards to some emissions issues I was having. I searched the thread and it apparently got closed. I'm taking a chance re-posting after several attempts to fix the issue without success. Please don't flame me for this as I'm really trying to figure this out and it is my daily driver. Here's the backround. 1994 Toyota Pickup with a 7MGE swapped in. All the electronics are 7M and the only change is that the EGR was deleted due to space constraints. Here's the problem...consistently high CO and HC's. The attempts to fix......new O2 sensor(old one tested poorly), Intake was fabbed up to replace crappy setup I had, Seafoamed the engine(vacuum line access, not in the fuel), Spark plugs(NGK) are new(rechecked the gap and color, looking good there), New plug wires(NGK), new catalytic converter(I believed the original was shot due to a small head gasket leak I had several months ago). I've tested the AFM and TPS which both show within specs per Cygnus, charcole canister is good and the gas cap seems right. Checked the timing and set it at 10 degrees with the jumper in, idle sits right at about 750rpm. Since I've done these things the truck has run great, not that it ran poor to begin with, and the idle is as smooth as ever. Problem is that the sniffer does not like it. Now it only has one cat and the mechanic at the testing site believes that it needs to have two. This isn't CA emissions, not as strict, but maybe he is right and the engine was setup to have two so the numbers won't be right until there is. I know that the computer is testing my truck as a 1994 and not for the 1988 emessions that the engine is putting out, but even then the numbers would be too high.

At idle: HC PPM 587
CO% 6.03

2500 RPM: HC PPM 152
CO % 0.92

So what do you all think? I appreciate any helpful suggestions. I honestly feel like I've done a fair amount of legwork on this and have made little to no improvements! Very frustrating and I feel like I'm just missing one thing.

Thanks a ton.

 

[3p141592654]

Post up oxygen, CO2, and NO numbers and we might be able to help.

 

[Cochip]

Don't have them, it's not part of the emissions testing. They have offered a four gas analysis, but more for helping to tune it while on the four gas to get it right and then quickly put it on the emissions machine. Honestly I didn't go for that as I'd like to find the actual issue.

 

[3p141592654]

You need data to solve problems. Validating you are in fuel control would be a good start. Do you have O2 cross-count data at 2500 rpm?

 

[Cochip]

No cross count data, don't personally have the ability to get that and I'm not sure where to go to get that done. I could recheck the new O2 sensor to make sure it is fluctuating as is should be. How would knowing how often the reading crosses 450mv line help in this case? I understand how the O2 sensor works in general, just not how this reading would help. Thanks

 

[3p141592654]

You just need a voltmeter to measure the swing between hi and lo voltages of the O2 sensor. If its cross counting at the required speed then its probably in fuel control. Better would be the 4-gas numbers.

 

[jetjock]

Edit: After reviewing the previous thread my current advice is withdrawn and the prior advice restated:

Resolving a loss of fuel control/mixture issues is automotive 101. If you're unable to do it on your own I'd suggest saving yourself frustration by taking the truck to someone more knowledgeable. Any half ass/back yard mechanic should do.

 

[Cochip]

I had considered the 4 gas analysis, but figured that I have two of those numbers already and one of the other two(NOX) is going to be high due to the deleted EGR. With that I just assumed that it wouldn't be very helpful. Am I wrong there? BTW what are your thoughts on one cat vs two? The mechanic at the emissions location seemed to believe that just about every vehicle out there is built with CA emissions in mind which would have had two cats with this engine. The reason I ask is that just about everything I have done has not changed the tailpipe numbers, but has improved the feel of the vehicle.

 

[Cochip]

Edit: After reviewing the prior thread my advice is withdrawn.

I hoped to quash this with my intro on this thread. Sorry that it went the way it did with the last one, I just felt you were a bit harsh and like you do with people who don't do their homework with these engines I tend to call it like I see it when someone is being a bit much. Either way I'd hope to get some help and I did do some work here on my own, not looking for an easy answer at all. Either way I hope somone like yourself with such good knowledge of these engines can help me to figure out this mystery because I really do want this engine to run right. BTW I didn't get a chance to see your advice so maybe you have a change of heart? Thanks

 

[3p141592654]

You need a 5-gas to get NOx. To repeat my previous post, there is nothing to be done here without first providing some data. You seem unwilling.

 

[jetjock]

I dislike getting involved when these engines are modified because people usually introduce all sorts of problems.

As 3p pointed out the engine needs to be in fuel control. A stoich feed gas into an operating catalyst is all that's needed. Although that's basic automotive repair not specific to this car you haven't, by your own admission, checked for cross counting and apparently don't know how even though the procedure is in the manual and also not specific to the car. Unwilling indeed.

I'll say this though:

1) It's rich at idle. So rich that gas analysis shouldn't be required to find the problem.

2) Assuming everything else (timing, spark, fuel pressures, injection, etc) is correct the ECU is more than capable of getting the mixture within 1% using nothing more than the load and speed signals.

3) At stoich the exhaust stream would be less than 6% CO with *no* cat.

4) Like most problems on the car this one is unlikely to be caused by an EFI system fault. That's not to say it won't be responsible, only that it's rarely the root cause.

 

[Cochip]

You need a 5-gas to get NOx. To repeat my previous post, there is nothing to be done here without first providing some data. You seem unwilling.

Please don't misunderstand I'm not unwilling just not able to give you these numbers you ask for at this time. I have work and family obligations that keep me busy as I believe you would understand. I don't have the ability to check the O2 sensor cross over readings, but I will look to see what the O2 sensor should be fluctuating at while at 2500rpms and test it. I imagine this number will be good as I just replaced the O2 sensor which tested well when I tested it just after installation. As I would imagine you understand that I have other obligations that keep me really busy and most if not all of my post will be when I have a chance at work. So I'm gather information and when I have the time I will apply that information and attempt to get any data I can to help this process resolve. Thanks for you help.

 

[Cochip]

I dislike getting involved when these engines are modified because people usually introduce all sorts of problems.

As 3p pointed out the engine needs to be in fuel control. A stoich feed gas into an operating catalyst is all that's needed. Although that's basic automotive repair not specific to this car you haven't, by your own admission, checked for cross counting and apparently don't know how even though the procedure is in the manual and also not specific to the car. Unwilling indeed.

I'll say this though:

1) It's rich at idle. So rich that gas analysis shouldn't be required to find the problem.

2) Assuming everything else (timing, spark, fuel pressures, injection, etc) is correct the ECU is more than capable of getting the mixture within 1% using nothing more than the load and speed signals.

3) At stoich the exhaust stream would be less than 6% CO with *no* cat.

4) Like most problems on the car this one is unlikely to be caused by an EFI system fault. That's not to say it won't be responsible, only that it's rarely the root cause.

Thank you for your reply and your observations. I want to clarify that I'm not a mechanic, but I am interested on learning about this, that is why I'm here asking questions. BTW the only change to this engine is the EGR which I understand would not be the cause of such a high CO and HC. It is the same engine merely bolted to another transmission. It has passed this same emission before the swap so I feel like I'm missing something obvious or something has gone sideways since the swap. As I told 3p I will recheck the new O2 sensor and get you all the data on it and see what you think. I checked the fuel pressure with the swap and found it to be more then adequate from the trucks fuel pump and have not honestly checked the injectors. Could be that one of them is leaking and dumping too much fuel in the cylinder which at idle is overwhelming the spark plug and pushing more fuel through the exhaust.

 

[3p141592654]

It's unlikely to be cross counting at all, and you could also measure the Vf pin on the diagnostic connector, which is also likely to be pinned at 0V. But this all seems pointless, since you say you do not have the time or skills to fix it. No?

 

[Cochip]

It's unlikely to be cross counting at all, and you could also measure the Vf pin on the diagnostic connector, which is also likely to be pinned at 0V. But this all seems pointless, since you say you do not have the time or skills to fix it. No?

I'm not sure if your reading my post completely, alas I'm here for help, not a fight! I will check the one week old O2 sensor and see if a got a dud from the auto parts store. I feel that I'm learning much more from this process and feel that I have a better knowledge of how this engine works because of this issue. I will not be stymied by my lack of progress on this and when I'm not on shift, like I am right now, I will work on checking some of these things. Again thank you for your insight and direction as honestly it is helpful.

 

[IJ.]

Either buy the tools need to provide the information asked for or take it to someone that does... :nono:

Going to close this as it's going no where again..

Don't start another thread on this subject unless you're willing/able to do as asked.

 

[Supracentral]

To clarify IJ's statements; Once you've done the tests that have been requested, feel free to start another thread, providing that information, and you'll get all the help you could ever want. You've got experts, real experts trying to help you here. The one thing they tend to hate is having their time wasted. So get the data and then post up a new thread, or PM one of us and we can reopen this one for you. Without the data it's all speculation, and that's a waste of time.