Alright guys, I have been searching and replying to other threads for the past couple weeks to no avail. 89 S5 NA with a goofy motor. Rebuilt ~8500 miles ago - check the sig, no problems until now. I have emissions deleted and a corksport exhaust with a couple leaks. It's built properly, just frankenstein.

FIRST, the problem and my observations. She starts, cold and hot with no problem, idles just fine. Free revs all the way to redline 9/10 times, but sometimes I get hesitation at 6500rpm. Drives great and pulls strong all the way through 1st, and then every other gear is just up to 6500rpm before I get a large drop in power and much hesitation/misfiring.

I have codes at idle, so I shut her off and checked them. My codes are 18 - narrow range TPS, which I need to adjust via the screw. Question is, I have never gotten the same/right readings since my rebuild/port job, but it runs great. When I drive, the light doesn't stay on, only does it come on when I take my foot off the gas. When I adjust vdc to near the spec voltages, it won't run, or it will at idle and if I touch the gas at all, I get wild hesitation, so I have kept my goofy settings. I probably need a TPS - no need to remind me. I also get 30 and 33, which are evidently solenoids for split air and port air bypass respectively. With no emissions, I reckon these will stick around with stock wiring, so standalone or piggyback, etc.
Here is where it gets interesting. Reading other threads I have found that [thanks to Karack] that the primaries can only sustain themselves up to ~6300 until they must have secondary input, or else you get lots of misfiring, which matches my symptom. I throw a code 71, which is for the front secondary injector.
18, 30, 33, 71

HERE IS WHAT I HAVE DONE - I replaced most of the grounds. I'm going to have to get a UIM gasket so I can pull it and replace my rear housing ground, but everything else is done including the starter mounting bolt ground. Yesterday I borrowed a multimeter and looked at my goofy tps readings again and did some playing. I got it to accept WOT all through the range with no hesitation, but at the expense of a few misses and hiccups while driving a constant speed - no code except at idle still. The hesitation came back not too much later so I put the TPS back at what it started at. I pulled the plugs and cleaned them very well. They were all caked with brown/black gunk, but the fronts were bone dry. Rears were very slightly damp. I cleaned them up and put them back in in the SAME places they came from and she ran better. Solved the problem for a little bit again and the hes. came back.

WHAT I NEED TO KNOW - is what's happening? Am I on the right track with checking grounds [they have all been gnarly so far]? Am I missing signal from the front secondary injector to the ECU?
How do I get to the ECU under the passenger side, which metal box is it, and which pins are for the secondary rail? Am I going to be testing for AC or DC volts, or ohms resistance at these pins? Do I need to replace the injectors, or test the voltages at the plugs? AC or DC volts? Is it possible that my ECU is not reading load on the engine from atmospheric pressure sensor without code 14? This car is my daily so I'm trying to keep downtime to a minimum if I can.

 

30 and 33 are there because you removed the ACV, you can ignore em.

18 should be fixed, i like to adjust the TPS with the factory 2 light method, as its an output and not an input.

however 71 i think is your culprit. for the front secondary injector, power comes from the main relay to the injector, and then the wire goes to the ecu, where it gets grounded.

first thing to check here is the simplest, make sure its plugged in, and that the pins didn't back out. next easiest is to check for voltage, the black/white wire should have 12V with the key on.

for the next step you'll have to peel back the carpet and check for voltage at the ECU

 

For the S5, the secondary ECU pins are 3X -front (Light Green/White wire) and pin 3Z-rear (Light/Green/Red wire). W/key to on they should read 12 volts dc (no voltage and you have a loose injector plug or one of the two wires is pulled back within the plug). As they come on line the voltage will drop to around 6 to 8 volts or so. The ECU is under the passenger carpeting close to the firewall. You'll have to remove the kickpanel and door scuff plate and then roll over the carpeting from top right to lower left. This exposes the silver protective panel on top of the ECU. Panel has four bolts, two at the bottom and the other two at the firewall. Pull the panel off of its mounting studs and it will expose the ECU. Secondary pins are in the largest ECU plug.

And the code 71 was an important piece of info to share.

 

You guys are great. Hopefully I can report back soon with some voltages if I can get a multimeter in my hands again today. Mine keep melting from sitting in my car or getting stolen.
I just want to clarify, I'm checking for VDC in these wires? Red probe to black wire in injector plug, black probe to battery? Can I warm the engine up, shut it off and open the throttle to watch the secondaries go down to 6-8v, or do I need to do it with the car running? I'm not great with electronics at all, so this is gonna get me better versed in these sorts of things.
Also, I HAVEN'T gotten to the ECU ground on the rear housing yet. If I get wacky voltages on these wires, I want to test at the ECU, replace that ground, then test at the ECU again.
Wacky voltages could be bad plugs or backed-out wires too, so I'll have to see as I go.

 

the easiest way to verify the secondaries is by the test mentioned in the other thread by swapping the primary and secondary injector wires at the ECU. if the car has symptoms of running on only one rotor then disconnect each secondary injector until the engine stalls and the opposite injector or wiring is at fault.

before going that far i would simply check the ohms of the secondary injectors since they are easy to access on an n/a engine. if either is beyond 12-14k ohms then replace it. and check the clips for corrosion, pins backing out, frayed wires, etc.

 

Karack, that is one thing I had been pondering making that connection but was unsure. Thanks for the clarification.

Is it safe to say I should try my best not to drive the car until I get this sorted out? The last thing I'm trying to do is detonate in a lean spike and have to rebuild my daily AGAIN. I really need a wideband for situations like this.

 

it's quite difficult to blow up an n/a engine unless it is already due for a rebuild anyways.

i honestly wouldn't worry about it and keep at the diagnosis until you figure out the problem. if it was a turbo then the steps would have to be a bit more delicate.

 

DC voltage is what is being measured. You can check while driving or you can check while idling but you'll have to place the engine under load which is achieved by unplugging the TPS and pulling the vacuum hose from the Pressure Sensor. At the ECU the Red meter lead goes to the ECU wire and the Black meter lead to one of the ECU mounting bolts which serves as your ground source.

 

Thanks again, fellas. Got dark, and I got a multimeter so I'll pull my passenger side apart tomorrow if I have to. I'll test at the injectors first, and then at the ECU, 3Z and 3X.

Karack, which wires do I check? The light coloured wire or the black one? I'm assuming the light signal wire. I'm kinda colourblind so you must excuse me. 12k-14k ohms or more and I need to replace the wire, plug or the injector? Perhaps in that order. If I can't get a decent reading from the plugs, I'll move to the ECU, then to swapping the pins as previously mentioned.

Also, Ben, Atkins' cryo-treated materials are bar none as I'm sure you know. I used all cryo-treated materials and ceramic 3mm seals from them as well. Hopefully I won't have too much of a problem and I can fix this soon.

Is it possible that front secondary injector is going bad or is it most likely a wire to or fro? When the sun comes up, I suppose I'll find out and let you guys know. I'm really not trying to tear my car all apart since I have work tomorrow too.

Satch, are you talking about the pressure sensor by the passenger shock tower?

I'm trying to plan everything out ahead of time so I can work as efficiently as possible tomorrow. Not too much time.

 

Yes. And the B/W wire powers the injector. Wires from the ECU trigger the injector to activate (Light Green wires). If you have 12 volts at the ECU pins w/key to on then the injector is receiving power via the B/W wire. You can basically focus at the ECU first as opposed to both ends. And the two terminals of the injector are used to measure the ohms. Place one meter lead on one injector terminal and the other meter lead on the remaining injector terminal and w/the meter set to ohms it will tell you what it is.

 

Thanks again, fellas. Got dark, and I got a multimeter so I'll pull my passenger side apart tomorrow. I'll test at the injectors first, and then at the ECU, 3Z and 3X.

Karack, which wires do I check? The light coloured wire or the black one? I'm assuming the light signal wire. I'm kinda colourblind so you must excuse me. 12k-14k ohms or more and I need to replace the wire, plug or the injector? Perhaps in that order. If I can't get a decent reading from the plugs, I'll move to the ECU, then to swapping the plugs as previously mentioned.

Also, Ben, Atkins' cryo-treated materials are bar none as I'm sure you know. I used all cryo-treated materials and ceramic 3mm seals from them as well. Hopefully I won't have too much of a problem and I can fix this soon.

Is it possible that front secondary injector is going bad or is it most likely a wire to or fro? When the sun comes up, I suppose I'll find out and let you guys know. I'm really not trying to tear my car all apart since I have work tomorrow too.

Satch, are you talking about the pressure sensor by the passenger shock tower?

I'm trying to plan everything out ahead of time so I can work as efficiently as possible tomorrow. Not too much time.

 

Sorry for the double post. My internet hiccuped.
Seems like I know everything I need to now for these tests.

I'll come back in the morning with some pictures and numbers for you guys. The amount of threads I have seen and replied to concerning this issue amasses much confusion it seems like, so I want this thread to be the end-all-be-all for this problem if I find my solution quickly with these test results.

That being said, if I have a bad injector [over 13k ohms], do I need to replace them in pairs or can I get just a secondary of the same volume? IIRC, the NA secondaries are 550cc? Mine are stock. If I need to replace the injector and since I need to pull my UIM to do the ground under there anyway, would it be a good idea to upgrade all four injectors if I plan to add a standalone and do some tuning at this point? I already plan to check/replace oil injectors and the OMP lines while I'm under there. Any other while-I'm-here... jobs during UIM removal?

 

Okay guys update time.

I have been working like mad, but I got some time to pull the plugs off the secondary injectors to check for resistance. Warmed up, I got right around the low side of 10k ohms on both front and rear secondaries. Mustn't be the plugs, but could it still be the wires?

So while I still have some light, I'm gonna go check volts at the pins. I just need to know which ones. I know it's the big section of the plugs. 3Z will be my target since I have code 71.
After that, regardless of the result, I will verify the secondaries. Ben, got a preferred method to pulling those pins out and replacing them? Again. Daily. I must do it right the first time.

Thanks, gents.

EDIT: I must add, upon looking at the wiring diagrams in my Haynes manual, the bottom picture on p.289 is the continued N/A EGI/emission control system diagram, which shows the injector wires from left to right; R2, R1, F2, F1 at pins 3F, 3C, 3H, 3E respectively. Is this right for an N351 ecu?

 

The foxed.ca wiring diagrams are great, but without a printer it does me no good. When I zoom in to see the pinout, it is super blurred. The Haynes guide says my wire is light green/white, but the diagram is split into three images of different rows, not inside an outline of the plug. I am still unsure if I need to find 3H or 3Z. I need to know where this wire is before I go poking and prodding.

Also, discovered the secondary rear injector plug likes to come unplugged because the catch on the plug is broken off. So who knows where I can get new injector plugs? It will hold on with dielectric grease no prob, but I don't want to worry about it at all.

 

Post #3?

 

I know. Just hadn't seen the pinout for the plug before. Thank you for your 3Z though. After some searching I finally found an image of the pinout for the N351 HAILERS posted eons ago and saved 'em all. Hahah. I'll have to get to testing again tomorrow after work.

 

With regards to the injectors an S5 is an S5 so if you find a pinpout for the S5 then it doesn't matter. Secondly, for the secondary injectors you can just pull the plug off to check for ohms.

 

I just wanted to find one that showed the pins in their locations on the plug, for clarification. I did test for ohms the other day and I saw ~10k on both secondaries, key to on, operating temp.
Could that injector just be stuck closed?

Still going to do the tests with the pins after a brisk drive home from work today and I'll post results.

Also, this is of no relevance, but WOO GO 'NOLES

 

The plugs are supposed to be removed from the injectors and then you test for ohms. Secondly, testing for ohms w/the key to on can damage the circuitry being tested so this is a no no unless you were testing the injector's ohms w/the plugs removed, and if so, then turning the key to on would serve no purpose.

 

I removed the plugs when I tested ohms. The rear one just doesn't lock back down because it was broken. I just also thought I had to have key to on when I tested that.

I also want to check fuel pump pressure for ***** and giggles just to see if the fuel pump is old. When I went in there to do the gasket, it looked relatively new, but that was a year ago, most of which time, it sat.

 

Can I just clarify. I'm going to warm the car up and drive it a little before I do this, but with just key to on for testing voltages, I can simulate the engine being under load by pulling vacuum line from pressure sensor and unplugging TPS, but is that simulating the secondaries coming on? Is that when I'm supposed to see 6-8v?

 

You need to raise the idle speed above 3800 rpm to activate the secondary injectors. Secondly, the ECU could be trying to activate these injectors fine and dandy but if the connection to an injector is iffy then it's a moot point.

 

Makes sense.
3X - 12.2v with key to on, cold and hot. 14.1v at idle.
3Z - 0.9-1.0v with key to on, cold and hot. 0v-1v at idle.

That rear secondary plug is broken and won't lock into place, so it probably slips out. All of the wires are still nice and snug in the weathertec connectors for both plugs, however.

As stated previously, around 10k ohms on each plug with key to on.

Is it possible I was misinformed on the code 71? Could it be for the rear secondary instead?

 

I went to try and ohm the plugs again and got some weird readings. No key, got 28.75k on the rear and 0k on the front. Key to on and warm still got 0k on everything.
I'm using a digital meter that you have to press mode to make it change from k ohms to M ohms, and it changes the decimal place on the screen. Never used one like this before. Am I just doing it wrong?

 

can't ohm test a circuit with power applied to it, it's also bad for the meter and might have killed it.