KrisD1

Hi, I have an 89 s5 turbo2. When I push the throtlle more than 1/2 it begins misfiring/flooding and the rpms drop, when i let go of the pedal it regains iddle.
I put in a new fuel pump/filter, checked the injectors and looked if the plugs give spark, that's all ok. Now I checked the ecu and found out that 3C/3D(ground) and 3H(crank angle sensor G-) are shorted. Is this normal?

HAILERS

It depends. IF you have the plug off the ECU, then none of the CAS wires should be going to gnd.

If you'll take the time, download the FSM and look at page B1-a and you'll see 3H is tied to one side of the two coils inside the CAS which is fine as frog's hair. But if you have the ECU plug off, and put the meters negative lead to a known ground, and the positive lead to each of the CAS pins in the ECU plug (plug off the ECU) then if you have the meter on ohms no continuity should be shown i.e. not grounded on any of the three CAS wires in the ECU plug.

CAS almost never fail even after twenty five plus years, Unless someone pokes around in their internals.

This is one of the FEW times I'd think the TPS was corrupt. What are the CODES given when the ECU is waterboarded?

KrisD1

Thanks for the replay, when the ecu is disconnected and I messure @ the pins of the ecu (not the plug) then 3C/3D and 3H are shorted, so 3H connects to ground.
Already checked the cas, and that's all good.

Problem is I can't check the engine codes, don't have the check engine light in my model, and when I connect the green check plug to ground and a 12V led between ACC and DCC1 it keeps flikkering.

HAILERS

Maybe go to the Fuel and Emissions section of the FSM and find the page Control Unit which lists the input/output of each pin, and while at idle, backprobe each of the wires and compare your reading with the results on that Control Unit page????

I don't know why the ABR is flashing all the time. And I also don't know if YOUR type series five, without the ENGINE light, will respond to interrogating the six socket plug like a USA car would if series four. IN fact I'm not sure one way or the other if codes can be checked like that on a USA version. I don't have a series five. Maybe someone who reads this and has a series five can verify a series five can/cannot be checked for codes using the green six socket check connector.

The problem sounds a little like a corrupt tps or airflow meter. Just a wild guess.

And yes, I should have realized you were checking the ECU and not the plug that attaches to the ECU. Makes sense for all three being tied together inside.

KrisD1

Thanks for the help, first thing I will do is test the ecu like said in the control unit page. Hope that someone can tell me how I can check the codes?

KrisD1

Ok did the test, these are the results( @iddle)
- 1K: fuel pump resistor relay stays at 12.2V (after more than 90secs)normaly below 2V
- 1V: ignition coil(trailing) is 1.04V, normaly 4V
- 2C: oxygen sensor: 0.07V, normaly below 1V(0.4V-1V I think)
- 2E: water thermosensor stays @0.5V , shouldn't this rise to 2.4V?
- 2F: throttle sensor (narrow range) is 2.04V, normal is 1V
- 2G: throttle sensor(full range) is 1.13V, normal is 0.8V
- 2L: intake air thermosensor(engine) is 4.13V, normal is 1-2V
- 3R: duty solenoid valve is 14.04V should be below 2.0V

So what can I do? Will change the iat and tps and disconnect the duty solenoid valve(have an avcr) and oxygen sensor. But what about the ignition coil?
Could it be that the ecu is faulty

HAILERS

IF the engine was fully HOT, then the first thing I'd do, is keep the engine idling and adjust the TPS so it output one volt dc. I'm not familiar with series five TPS. I assume they have an adjustment screw.

Odd the fuel pump voltage does not drop down below 2vdc. All it means is , is the pump is getting a full 12vdc instead of the 9vdc it usually sees when no Load is on the engine. This MIGHT be related to the TPS output and or the boost/pressure sensor output. Check it again after you adjust the TPS to one volt dc when the engine is FULLY HOT.

Water thermo sensor should output, when the water/engine is fully HOT, about 0.4 to 0.5vdc. Been there, seen that too often to be wrong about it.

Check this water thermo sensor voltage some time when the engine is cooler. Just key to ON engine OFF. The voltage should be much higher, depending on the water temperature. Usually if the engine is cold, and your monitoring that water thermo sensor output, the voltage will be high, like 2vdc or so, then as the engine warms up the voltage should drop gradually til it reads 0.5vdc or so. The 2vdc is just an example. The colder the water the higher the voltage. But when the water is 180* it should read 0.4 to 0.5vdc.

The intake temp sensor sounds like it's disconnected to me. That's why you'd see a high figure like that. It's the one at the throttle body intake, at least on a series four it is. Right where the intercooler outlet duct meets the throttle body. Plug off.

I'm not sure about the Duty Solenoid ....right now. You sure it's plug is on the duty solenoid?

1V should be reading approx 4vdc at idle. EDIT: oPPS. I read you wrong on that. Was the engine at idle when you did that? If at idle it should be approx 4vdc but if the key was just to ON anything below 2vdc is ok.

HAILERS

Oxygen sensor...........if the complete airpump and ACV plus the Relief solenoid and switching solenoid are on the car and working, then at idle you'll see a very low voltage. Maybe even 0.2 or 0.1vdc.

IF it's no emissions, no airpump, then at idle full warm you would see something on the order of 0.65 to 0.85 vdc. Normal figures for no emissions/airpump.

As an aside: I found out the o2 sensor on one of my cars, narrow band, was reading a negative voltage. Like -0.95vdc and the meter was connected right. I pulled that sensor and installed an old one out of a old downpipe. Reads 0.10vdc at idle with full emissions equipment. That one reads approx 0.65vdc if I *disable* the ACV/airpump. Never seen a screwed up 02 sensor like that ever before. Readiing a minus.

Do your trail sparkplugs fire?

KrisD1

1V was at idle, all emisions stuff is removed from the car.
What could be the cause of this? are the trailing coils broken or the ecu?
Disconnected the trailings, but engine runs the same.
Oxygen sensor looks broken to me, air temp sensor is connected.
There's a screw to adjust the tps, will do this again. The ohms are good.
When i look @ the output on my avcr the thottle sensor shows 1.12V for the iddle position and 4.56 for WOT, this looks pretty good I think, so it looks like the narrow range sensor is broken?
Fuel pump stays @ 12V
The car starts immediatly and iddles@ 750 rpm but sound really rough like a peripheral port.

HAILERS

RX run just fine without the trail sparkplugs working. You could remove mine in the middle off the night and I'd never know it the next morning if I didn't know the tach works off the trail coil assy.

Which brings up the question: Your tach work? IF it works, the trail coils working. The series four FSM says the feedback signal for the Trail coils should be less than 2vdc when idling. So..........I think there is no problem but I'll look at my car, ehhhhhhhhhhh........later. Maybe tomorrow, maybe tonight.

About the TPS. I know not about your ACVR , but if it's taking the signal off the NARROW range TPS, then that''s fine. The narrow range wire is a green/red wire at the ECU. So if your tapped into that, then the ACVR is right and TPS ok. Just a touch high, but approx is approx. That ACVR would be a good way to look for irregularities on the TPS. Just watch the voltage as you slowly go from idle to full throttle. Key to ON engine OFF. I say screw setting TPS by ohming them out unless your looking for shorts/open etc in the pot.

Yes, 02 sensor sounds shot unless the wire b/t it and the ECU is shorted to gnd or open. Go to the 02 sensor. Disconnect the wire at the 02. Put your meters positive lead on the 02 sensors connector. Other wire to a known gnd. Start the engine and get it fully hot at idle. The meter should read, in my opinion, about 0.65vdc to up to 0.85vdc if no emissions are on the engine. If it reads the 0.07vdc then it's shot imho.

Idling rough worrys me a bit. I'd pull the Lead plugs out. Put a finger/thumb over one lead hole and have someone spin the engine over for ten seconds or so.
The put your finger over the other lead sparkplug hole and repeat. If you've a bad apex seal you should be able to easily tell by the pulses b/t the sparkplug holes being quite a bit different.

Then again it could be a vacuum hose problem somewhere.

Fuel pump/resistor relay is a mystery. What the deal is, is the ECU outputs a gnd to the resistor/relay and that is what causes the voltage to drop to less than two volts. It outputs that gnd just after the engine starts and removes it when the ECU senses a Load on the engine. That wire is green/red also and comes from 1K on the ECU and the same colored wire is at the connector of the fuel pump/resistor relay. I'd take a look and see if something is amiss with that wire. Like ohm it out b/t the ECU and resistor/relay and maybe, with the plug off he resistor relay, see if the pin the green/red connects to on the resistor/relay package will ohm out from there thru the coil inside the resistor/relay. You'd ohm out where the green/red wire connects, to where the blue/red wire connects to the relay. The FSM shows which two pins on the plug and the approx ohms.

But the failure of that relay to pull in just leaves a solid batt voltage on the output to the fuel pump. That can't cause your problem. Although I'd pull the fuel pump connector off and take a look at the Blue/Green wire at the pump with the key to ON to see if it is batt voltage or not.

I don't know how to be short and brief. Bye.

HAILERS

Air intake sensor. I'd pull its plug off and ohm out the sensors two wires and compare the reading with the value in Fuel and Emissons seciton of the FSM. Or pull the plug off and then see if the reading at the ECU changed or not. That might be telling.

HAILERS

That trail coil feedback wire reads approx one vdc with key ON on my car and approx 1.3vdc at idle. Yours is ok.

KrisD1

Thanks for the feedback, my compression tester will arrive this week, hope it's not a broken apex. The avcr takes it signal from the wide range tps, so it could be that the narrow range is broken. Will also look again for vacuum leaks.
Also if the car is overfueling (maybe an injector that stays open) can it cause it to choke and not go into boost?

HAILERS

The injector grommets b/t the injector and the housing, if rock hard, can cause a bad idle. Choppy idle. They leak air is why. Not saying that is the idle problem, just one of many things.

At idle, if you pull the boost sensor vacuum line, do you feel vacuum being pulled? Just in case you connected the vacuum line to a non vac source.

Stock injectors? Stock afm? Stock boost sensor?

Since that ACVR uses full range tps, then I'd adjust the tps to what the figures in the CONTROL UNIT page say it should be at idle and a fully HOT engine. Not saying that is your problem, but you might as well set it to meet the figures in the Control Unit page.

KrisD1

grommets and o-rings have been changed. I feel vacuum being pulled.
Still have stock injectors,afm ,boost sensor. Only thing I did is run half premix with castrol tt oil (two stroke oil) maybe it's this. Or maybe the fuelpressure regulator is not working like before and pressure is to high? Will check this this week with a fuel gauge. Will also adjust the tps. Hope this will work and thanks for the help.

KrisD1

Well turns out Hailers has been right from the start
Well I looked around the forum a little bit and found that alot of us are having this same problem and someone with the same problem disconnected his TPS ,after this the iddle was good.
Just tried it and it purred like a kitten just like it has to be.
So what happened?
I did the throttle body mod and after I put it back on the engine would'nt start.
So I looked at the TPS and everything was still good.
Turned out I put the throttle lever wrong , so I changed it like before and the engine started but it iddled bad and would'nt go into boost.
Today I looked at the TPS again and everthing was way off, well the narrow range was OK, but the wide range was really bad, turned out the connection that holds the wide range sensor onto it's place was broken and this made that the sensor could move back or forward.
Tried to fix it and adjust everthing to the values given in the FSM but the car would'n start anymore, when i look at the avcr it gave 0.4V, so I tightend the throttle cable so the avcr gives 0.8V but now it iddles at 3000rpm.
Looks like I'm buying a new TPS. Hope that this solves the problem.
Big thanks to Hailers for helping me out.

HAILERS

Anyway a tps can be epoxy'd on the bracket? Not JBWeld, but some of that five minute epoxy or ten minute epoxy. I'd let it set up a lot longer than five minutes. Like over night. Just a thought. You'd have to have clean boding surfaces etc.

bob cutlip

Where do I download the FSM? 1990 convert. RX=7

texFCturboII

iTrader: (17)

Why doesn't your model have the check engine light? That's weird.....

KrisD1

It's a European model, i live in Belgium. If any one knows how to do it please tell me.

Bob:http://www.rx7city.com/techconnect.htm