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I'm not a tuner or a mechanic, but to my understanding replacing your ECU would remove that as a possible issue, you could keep the old ECU if you wanted the tune. It might be buried under a panel or two, but it should be literally a plug and play removal you can do at the parking lot of the dealership. Search "nicoclub g35 coupe FSM" for some good reading for learning more about your new car! If you want to own it for a reasonable cost you should get used to diagnosing and solving small problems on your own and performing basic maintenance on your own if you don't already.
The non-revup engine has variable valve timing on the intake valves only, which is visible on the front cover of the motor (Google Images: VQ35 revup vs non revup). They make less power and don't rev as high, but have more torque down low and don't have the fatal oil consumption issues the later revup engines had, which is probably why yours has been replaced. I wouldn't worry about it, although I would pull the spark plugs, change the oil, and monitor oil consumption for awhile as these cars all burn some oil.
That's actually where I got the service manuals I've been referencing. The forums seem a bit slow compared to here though but I will keep them as a second resource for searching common issues before posting here. I also do plan on doing as much myself as I can even though traditionally I do more harm than good.
As far as the Rev Up, is that why you think it was swapped to a 03-04? Because from my understanding (reading here) the 2005 5AT (which I have) doesn't come with the Rev-Up, only the 2005 6MT. Is there any other reason to believe that the engine was swapped? Not challenging you, just curious as I'm curious and eager to learn.
^^ You're correct. For some reason I thought you had a 6MT lol. So your engine is probably the original then, good researching!
Would the idea of getting a stock ECU still be possible though? I kind of like that idea as it seems like the cheapest starting point and I might not have to spend $700 to tune it.
Yeah, assuming that your only problem is in fact a problem with your ECU's communication with the OBDII reader. It might be more complicated than that, I haven't done it before but that's where I would start.
The non-revup engine has variable valve timing on the intake valves only.....and don't have the fatal oil consumption issues the later revup engines had, which is probably why yours has been replaced. I wouldn't worry about it, although I would pull the spark plugs, change the oil, and monitor oil consumption for awhile as these cars all burn some oil.
Not true sadly. The non-revs ARE prone to suffering the dreaded OC , just not as high a percentage of them as the rev-ups.
Wow you actually read all that? It's been a slow couple days at work lol.
They all consume oil, but at least in the time I've been on here I don't think there have been any non-revup people on here complaining about OC wheras I can remember several people with revups talking about OC in the 1qt/500 miles range, and they had less than 200k.
My non-revup goes through a quart every 2500 or so and it's been that way since 100k when I bought it, and you all know how I drive.
Mine doesn't seem to be burning oil yet, but I'll keep an eye on it.
I have some more information that may help diagnose what's going on. I took the car to DEQ when I first got her back in 12/16 and the only things preventing me from passing were an unready O2 Sensor and Heater. That is on that report, the Catalyst was showing ready but now after sitting with a dead battery for a year it is reading unsupported/unavailable.
I've read elsewhere that after sitting for a while the Cat may need to be warmed up through driving but that was with a different car with similar issues (Ford Focus iirc). Could it be that I just need to drive it until the Cat reads ready? Or would a tune have made it so the Cat read as ready but then after the battery died this got reset? Or is it possible they just didn't catch this before?
I can scan the DEQ reports of it helps, but I checked my torque screenshots from then and now and they read the same as below, (Catalyst Not avail). No fault codes when I check with Torque either time.
Wow you actually read all that? It's been a slow couple days at work lol.
They all consume oil, but at least in the time I've been on here I don't think there have been any non-revup people on here complaining about OC wheras I can remember several people with revups talking about OC in the 1qt/500 miles range, and they had less than 200k.
My non-revup goes through a quart every 2500 or so and it's been that way since 100k when I bought it, and you all know how I drive.
Our non-revup with 160K miles went through a qt. every 800-1000 miles. And now she's dead, RIP Amanda lol.
There is nothing in the electronics that looks directly for a catalyst. The only thing being done is reading the oxygen content of the exhaust gases and the ECU then draws conclusions regarding how well it is working. The OBD readings often do not tell you exact what is wrong but are more like clues. In this case the ECU is not getting correct 02 sensor readings and the problem could be anything from the Cat to the ECU such as the Converter itself, the 02 sensors and the cabling between the sensors and the ECU. I am not aware of any test for either of those components but that doesn't mean they don't exist. An emissions shop would know which is better than just replacing expensive parts hoping they will work. If I were forced to fix it without professional help I would start by getting it up on a lift and look for obvious problems such as and cutting/welding on the cats which could mean they have been modified, missing or damaged 02 sensors or the sensor cabling. If I had to guess which to replace first, converter or sensors I would go with the least expensive.
Originally Posted by jland13
Mine doesn't seem to be burning oil yet, but I'll keep an eye on it.
I have some more information that may help diagnose what's going on. I took the car to DEQ when I first got her back in 12/16 and the only things preventing me from passing were an unready O2 Sensor and Heater. That is on that report, the Catalyst was showing ready but now after sitting with a dead battery for a year it is reading unsupported/unavailable.
I've read elsewhere that after sitting for a while the Cat may need to be warmed up through driving but that was with a different car with similar issues (Ford Focus iirc). Could it be that I just need to drive it until the Cat reads ready? Or would a tune have made it so the Cat read as ready but then after the battery died this got reset? Or is it possible they just didn't catch this before?
I can scan the DEQ reports of it helps, but I checked my torque screenshots from then and now and they read the same as below, (Catalyst Not avail). No fault codes when I check with Torque either time.
There is nothing in the electronics that looks directly for a catalyst. The only thing being done is reading the oxygen content of the exhaust gases and the ECU then draws conclusions regarding how well it is working. The OBD readings often do not tell you exact what is wrong but are more like clues. In this case the ECU is not getting correct 02 sensor readings and the problem could be anything from the Cat to the ECU such as the Converter itself, the 02 sensors and the cabling between the sensors and the ECU. I am not aware of any test for either of those components but that doesn't mean they don't exist. An emissions shop would know which is better than just replacing expensive parts hoping they will work. If I were forced to fix it without professional help I would start by getting it up on a lift and look for obvious problems such as and cutting/welding on the cats which could mean they have been modified, missing or damaged 02 sensors or the sensor cabling. If I had to guess which to replace first, converter or sensors I would go with the least expensive.
OK that makes sense to me. I spent a good part of yesterday reading about how to get her in the air safely and have made a shopping list of what I will need. Sounds like I will need to get under the car to be able to tell more.
After examining my photos and comparing to the service manual and images of OEM cats, I am less convinced I have stock Cat's after all as they appear more like what High Flows would look like (pipe from exhaust manifold with O2 sensor, single bulge where cat would be. They just look dirty/rusty like what a used OEM Cat would so I assumed they were. I also couldn't get a good look from under the hood (not sure where exhaust manifold is and can't seem to find Cats) so it does look like gettng her jacked up is the first course of action.
I plan on buying the jack from Costco, a set of 4 jack stands from Autozone/Harbor Freight, and probably some 2x4's as it seems like my car is pretty low,and maybe some RhinoRamps for a backup safety measure if I can figure out which ones are safe to buy (Amazon's have bad recent reviews of cracking, Atutozone had a different brand).
Thanks for the help, I'll report back with more info and better pics after I get her jacked up.
This is what the 2004 cats look like. Ignore the pipes attached the the exit as that is part of an after market cat back system.
OK that is helpful thank you so much! I had a hard time finding any images with the OEM's installed. Here is best pic I could get of what I think are my cats, they look nothing similar imo and resemble more what dirty Hi-Flows might look like, at least in my limited knowledge and no experience.
They do not look like OEM (see parts diagram of an 2005). My cats have bolt flanges on both ends and I expect the 05's would have the same design. If they didn't change the plumbing on both sides of the after market cats changing back to OEM is as simple as removing 4 bolts. Actually mine were studs welded to the pipe on the front. I remember that because the front nuts were so tight it required a long breaker bar with an extension to reach in from the top.
They do not look like OEM (see parts diagram of an 2005). My cats have bolt flanges on both ends and I expect the 05's would have the same design. If they didn't change the plumbing on both sides of the after market cats changing back to OEM is as simple as removing 4 bolts. Actually mine were studs welded to the pipe on the front. I remember that because the front nuts were so tight it required a long breaker bar with an extension to reach in from the top.
Yeah, that's what they look like in the service manuals I've been referencing from Nicoforums, perhaps same one?
Well, it seems the pieces of the puzzle are starting to come together enough to where I can make a plan of action to troubleshoot this. It seems like I may have aftermarket cat's and I may or may not have working sensor's based off of the most recent servicing in 2015 according to CarFax. If I wanted to be safe I might want to start by replacing the cat's to OEM (and maybe the sensors), or at least trying to figure out what exactly I have by jacking the car up and if should pass DEQ first.
I'm still unsure on the state of the ECM, if I need to try and replace it with a one I can flash to stock ($100 by tuners, unsure on dealership ability price). This looks like it will be a $50-$150 part (plus the flash) and I would prefer NOT to mess with the current tune just to pass DEQ and not re-tune it unless I were to add something to it. I have a pretty good idea on the process for this from the service manual but one thing I am curious about is if I could get an ECM that's already flashed to stock, or if that's something that needs to be done after install.
Hopefully, I'm getting everything to jack her up today or tomorrow at the latest unless I have to get it shipped. I've also joined several Facebook groups (including ours) and am keeping an eye on Craigslst / Offerup /here and eBay (worst case) for some Cat's (+/-Sensors) and ECM.
01-17-2019, 10:49 PM
