04-29-2022, 02:25 PM
Ok so I have a bit of an update. I spent an entire day with my buddy (who has a few spare engines and intakes) and started swapping parts. In total I tried swapping:
MAF
ISC
EGR Main
EGR Modulator
EGR VSV
Plug caps & wires
Distributor Cap
Distributor Rotor
Nothing made a difference. I ended up swapping back to my EGR right before I left to go home but left the rest of his parts on there. On the way home I noticed that the stuttering was gone! However I was having idle issues. The car actually died once at a stop light. I drove it like this for a few days until today when I decided to diagnose and hopefully fix the idle issue. Swapped the ISC again which made no difference and then tried to swap the EGR. Once I pulled the EGR off I saw what was really going on. While putting it on I had managed to let the gasket slip off of the top bolt and it was covering one of the holes. Once I fixed this gasket and tested it again the stuttering was back.
My new theory is that my ECU is bad and is constantly restarting which is then triggering the VSV to cycle closed (allowing the EGR to open and introduce exhaust gas to the intake, making it bog) and closed (closing the EGR and letting the engine recover). I was looking at this the below image and I'm assuming that the VSV is used to vent pressure at light load and corresponds to the bottom left "0 EGR Ratio" part of the graph.![[Image: egr-gas-profile.JPG]](https://fixkick.com/sensors/EGR/egr-gas-profile.JPG)
If this is the case then I think the ECU might be the answer. I'm going to open it up and see if there is any obvious corrosion. Otherwise I'm going to replace the injectors but I don't see how that would help.
Car also idles a bit low, when coming to a stop it will sit at 800 for a few seconds but then drop down to 600-650.
So to conclude it's still is annoying and makes me want to bang my head on the steering wheel.
Thanks!
MAF
ISC
EGR Main
EGR Modulator
EGR VSV
Plug caps & wires
Distributor Cap
Distributor Rotor
Nothing made a difference. I ended up swapping back to my EGR right before I left to go home but left the rest of his parts on there. On the way home I noticed that the stuttering was gone! However I was having idle issues. The car actually died once at a stop light. I drove it like this for a few days until today when I decided to diagnose and hopefully fix the idle issue. Swapped the ISC again which made no difference and then tried to swap the EGR. Once I pulled the EGR off I saw what was really going on. While putting it on I had managed to let the gasket slip off of the top bolt and it was covering one of the holes. Once I fixed this gasket and tested it again the stuttering was back.
My new theory is that my ECU is bad and is constantly restarting which is then triggering the VSV to cycle closed (allowing the EGR to open and introduce exhaust gas to the intake, making it bog) and closed (closing the EGR and letting the engine recover). I was looking at this the below image and I'm assuming that the VSV is used to vent pressure at light load and corresponds to the bottom left "0 EGR Ratio" part of the graph.
If this is the case then I think the ECU might be the answer. I'm going to open it up and see if there is any obvious corrosion. Otherwise I'm going to replace the injectors but I don't see how that would help.
Car also idles a bit low, when coming to a stop it will sit at 800 for a few seconds but then drop down to 600-650.
So to conclude it's still is annoying and makes me want to bang my head on the steering wheel.
Thanks!