Intermittent rich codes and SAIS? (1 Viewer)

[Broham]

Ive been battling these codes 0172/0175 off and on for a while. Firstly I did change the MAF a while ago, this did work for a while, then the codes came back. Even if I'm not getting the light, I can tell by the way the truck drives. ie holding gears, rough idle, erratic shifting and revs. I went though and checked for and vacuum leaks, cleaned TB/MAF, replaced coolant temp sensor. Again, mildly successful but ultimately came back. It will go away on its own from time to time, and emissions when its off will pass. It finally came back again, and I decided to take it into my local indy since I got tired of chasing it, and I needed a few other things looked at as well. He told me it had a SAIS installed, which I do faintly remember when bought the car a few years ago. At the time of purchase I was not super familiar with it, but I did manage to dig up the paper work on it, the one I have is from Hewitt-Tech. When I started shopping these trucks, I did decide on the VVTi motor, and some of the refreshes. Not fully knowing about these air injection systems. Although there is a power increase, it seems at a potential cost. My understanding on these is that its more of an emissions issue, and all the parts involved can be problematic and costly over time. Im guessing I Had the whole kit installed, plates and module of course, but dont see why this would cause rich codes. Tech unplugged the module and said it was fine afterwards, I'm assuming the plates are still installed. If the system is to be removed, should I remove the plates as well or is it okay to run it that way? Do these modules tend to fail over time? He also told me that the fuel trims were fine. Any input would be appreciated.

Matt.

 

[nothappening]

You're going to end up with more codes if you leave the plates in place because the system will recognize that the passages are blocked off. If what you have is a Hewitt Tech module, email/call them directly and they will help you troubleshoot.

edit: The 06 and 07 had the Secondary Air Injection System (SAIS) and the kit is to bypass that system. It only operates on a cold motor start condition to reduce emissions afaik so it would be strange that it would create an ongoing rich fuel mixture, I don't know how those systems would even be related.

 

[Broham]

exactly, this is why im curious. The rich codes must be coming from something else entirely, or perhaps the module is bad. I have thought the replacement MAF could be faulty *I love getting faulty parts*. The module perhaps is interfering with the MAF reading. Ill email the company and see what they say

 

[jerryb]

it's not the by pass kit. IF you wanted to take it out though removing the plates is easier than installing them.
the module does interfere with the MAF measuring, but it should not do what you're describing.
You probably just need a real tune up, checking all the hoses, watching misfire count, fuel pressure check and leakdown time. PLugs, coils and boots. MOnitoring short and long term trim. long term hits a light at 22% I believe.
Girlfriend driving and monitor with teachstream, OBD fussion torque etc, hot and cold start and driving. Pretty simple.
I'd think its just a hose, a coil, a fuel pressure thing or a plug, boot, coolant temp, o2 volatge.
A good question to ask hewitt would be, what happens if your bypass fails?
I bet nothing except more codes.

 

[Broham]

I changed the coolant temp sensor a while back, did a tune up when I first got it, not boots. Changed one hose, because it was cracked, however I hear no hissing. My next steps are fuel issues, like you said regulator, injectors etc. Its super interment, Even if the lights are on or off, I can tell just by the engine speeds, and bad shifts. I'll report back when I find further. Thanks for the input errbody. Oh, I also assumed that maybe I just got a bad MAF, but I figured if thats the case, this would be on all the time. Also by just unplugging, the engine dies. Is this in fact a good indicator the MAF is good?

Matt.

 

[Broham]

Also someone help me out with what these lines are? the one seems a little taught.

 

[jerryb]

vacuum hoses from the vsv(s) where you left index finger is around both.

it's weird he said the fuel trims were fine. I wouldn't believe him and check myself. the only way to get those codes is the ecu subtracting more and more fuel and then the CEL sets.
IN that instance alone you'd need fuel pressure and regulator check and misfire counts. Open and closed loop cycling, o2 readings.

OBD fusion has good misfire screens on a phone. I've never used torque to look at that info, or couldn't find it as easy in the app compared to fusion. Techstream would be best. But it's hard to look and drive at the same time on a laptop.

normally- unplugging a maf will make the engine die but there are instances where it could keep idling, but not steady. Temp and pressure dependent.

this info here explains it far better than I could write.

copy and paste it.

repairpal.com/obd-ii-code-p0172-and-p0175#targetText=An%20%22over%20reporting%22%20Mass%20Air,a%20code%20P0172%20and%20P0175.&targetText=It%20is%20important%20to%20restate,of%20air%20entering%20the%20engine.

 

[Broham]

Heres what I got...

 

[Broham]

Seems the LTFTs were in super negative. I changed the MAF again, and the PCV, and hose. Now seems to be running better, and the trims are back in the positive. I seem to be getting good volts/data from the O2's. If it acts up again, ill have to look more towards fuel issues. Regulator, check plugs and injectors. I was looking for the Schrader valve on the rails but couldn't find it. Is it on the line somewhere else?

 

[jerryb]

No valve. You have to mount one on the port/banjo bolt crossover pipe.

If I suspected the pump I would just buy a new one and put it in, if I did not ha e an easy on hand way to check fuel pressure and leak down #s
100 for a new pump.

 

[Broham]

bumping this back up, problem sill persists, new egr valve, checked for vacuum leaks, nothing. Seems now im looking more for an exhaust leak pre cat. Or my up flow sensors are bad. I cant seem to check both independintely on my reader, but the upflow shows 3.3..or maybe that means .3..and the down flow is reading rich still at .6 The up flow sensors for the vvti seem higher priced that the earlier models. 120 a pop? this seem right? I may change both and see where Im at afterwards. thoughts?

 

[golfer2000]

Did you ever solve this issue?

bumping this back up, problem sill persists, new egr valve, checked for vacuum leaks, nothing. Seems now im looking more for an exhaust leak pre cat. Or my up flow sensors are bad. I cant seem to check both independintely on my reader, but the upflow shows 3.3..or maybe that means .3..and the down flow is reading rich still at .6 The up flow sensors for the vvti seem higher priced that the earlier models. 120 a pop? this seem right? I may change both and see where Im at afterwards. thoughts?