The previous owner must have disconnected the check engine light. At first I thought the bulb had burned out, so I changed the bulb but that didn't work so I bought another unit and put it in but it doesn't work either.

So, the PO must have disconnected the light. Now what do I do? Can I retrieve the error codes any other way?

 

There is a Green check connector located by the leading coil which has 3 wires to it. They are Black/White, Yellow and Yellow/Black. These are the wires that a LED check light can be wired up to pull codes on an S5. I don't have an S5 nor have I done this on an S5 but you'll have to experiment with whether you need one LED light or two like the S4 check light. The B/W wire has voltage w/key to on so if using a single LED then the positive LED wire goes to B/W and the other LED wire goes to either Yellow or Yellow/Black. If using the twin LED light then the two wires joined at the LED go to B/W and the other two LED wires go to the other two wires in the Green check connector. When the light is in place you might have to ground the single wire Green check connector, located next to the 3 wire Green check connector, to the battery ground terminal (negative) to start up the sequence in addition to having the key to on.

 

Thanks Satch. I appreciate your help. I'll give that a try.

ashley

 

Satch, I hooked up the led test lights and it worked just like you said. Great, thanks again.
I received 03, 33 and 38 error codes.
That is:
03 Crank angle sensor
33 Port air solenoid valve
38 Solenoid valve (AWS) and air supply valve (ASV).

My 7 is mostly emissions free and doesn't have either of the latter two. So, I'll swap out the CAS.

 

The problem still exists. I'm running out of things to swap out. I put a new Walbro 255 in and now the pressure is over 90 psi not running and 40 psi running. I also swapped out the CAS, since the ecu said it was bad but the ecu still says its bad and I know the CAS is good.
I have another boost sensor coming Monday. I guess I can hope that fixes it.

Unbelievable, it idles perfectly.......... 800rpm, with very little variance, the tach needle barely moves. Starts up with-in 2 secs but runs like crap.
IF I give it gas a little at a time, the engine will rev up but if I try to take off fast it will cut out and backfire.

 

The wiring/plug for the CAS might be the problem as opposed to the CAS itself.

By disconnecting the 3rd plug of the ECU and check for ohms (no key) between pins 3G (White wire) and 3H (Red wire) and between pins 3E (Blue wire) and 3H and it should read between 110 to 210 ohms as stated in the FSM.

 

.

 

i am having a similar problem. all parts are for s5. tps is turbo. wire harness is n/a. could this be a problem?

 

I checked the resistance of the two circuits and both circuits tested within the stated values.
Does that mean that the ECU is bad? Would it be possible that the problem lies with the RTek 1.7 chip? Is there a way to check the ECU to see if it is functioning properly?

Something else I noticed today. At idle the timing is dead on. At 1000 rpms the timing advances a few degrees, like it should. But, if the timing is raised to 1500 rpm, the timing jumps enough that the timing mark completely disappears. I can't remember if it should jump that much.

 

As far as I know, mine has all S5 T2 parts, ECU, harness, AFM. It idles great. Runs like crap. Actually its not drivable, absolutely no power.

 

I checked the resistance of the two circuits and both circuits tested within the stated values.
Does that mean that the ECU is bad? Would it be possible that the problem lies with the RTek 1.7 chip? Is there a way to check the ECU to see if it is functioning properly?

Something else I noticed today. At idle the timing is dead on. At 1000 rpms the timing advances a few degrees, like it should. But, if the timing is raised to 1500 rpm, the timing jumps enough that the timing mark completely disappears. I can't remember if it should jump that much.

 

I installed the N370 boost sensor but nothing changed. I checked for ecu errors again and this time I got a 27: OMP error, so I swapped out the OMP. After getting the OMP all hooked-up, the engine ran really good, no cutting out, no backfiring, perfect idle. But, it ran good for only 3-4 minutes. I took it out the road and ran the rpms up to like 4500 and it was boosting about 7 lbs when it backfired a couple of times and cut-out really bad. Just about the time I reached my driveway, the engine shut down and would not stay running. After I let it sit awhile, it restarted but it is exactly like it was before but it doesn't idle now, once I take my foot off the gas it stalls.
Sounds like limp home mode?????

Now what?

 

The 27 error code might have been a problem for a while. Due to the check engine light being out and only recently pulling codes manually, the ECU might be damaged.

 

my car wont even start unless i mess with the egi fuse and relay under the dash. even then, when it does start, it runs rough, doesnt idle, and smokes fuel out the tail pipe. when it stalls, it takes forever to get started. i have no idea what to do anymore. i have literally tried everything and cant think of anything else to do.

 

Does anybody do checks on the ECU to verify it being defective? Mazda dealership maybe?