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Injection issues - bad - & Throttle Body information request



  Clio 2 ph.2 - 172
Hi guys,
This is a long story short, at the moment I bought a CAN Clip to get deeper into an injection problem on mi 172 (ph2).
The problem came to light when I tried to start my car one morning and it was very low on fuel, but as I recall I arrived home the night before with any problems -just low on fuel-, I barely started it and drove it on fumes to the gas station (very bad, but I really was in a rush ), the car was juddering very badly, and couple of times it turned off so I clutch cranked it (2nd gear, then clutch out...). When I filled in some gas finally, the car did not start well, it was idling stupidly bad and hunting I needed to keep the gas pedal down a little to avoid stalling.
Extras: the car can start but it has very very bad idling, hunting, stalls if pedal gas is not a little bit down and it has BLACK SMOKE.
First thoughts based on what happened:
- I fried the fuel pump
- Dirt in the bottom of tank clogged one or more injectors
- A fuel line / fuel filter got clogged (yes it does have fuel filter, just under the gas tank, not only the mesh like one on the fuel pump)
- The diaphragm of the fuel pressure regulator got damaged by passing air-fuel-air while the tank was getting empty.

I ruled out all of those by:
- Took out the fuel rail and injectors and got them to a diesel injection laboratory for a ultrasound cleaning (guy said all of them were 98-99% and normal spraying pattern) so injectors were not the problem, I have clean injectors now...
- Changed fuel pump motor even when older one was still buzzing, maybe under pressure the story was different (did not solve the problem).
- Changed the whole fuel pump assembly, which included fue fuel pressure regulator.
- what I didn't perform was a fuel pressure test to make sure it is 3 Bar ...I'll try to do it, but I am 95% sure it is not the problem.
A little history, car got new ngk plugs and new leads ( 6 months before this), new air filter and cleaned Throttle body (drive by wire one) one month ago, new upstream lambda and temp sensor recently made. Also, I have checked that the dephaser solenoid is opening and closing...

After that, and based on the black smoke which means over fueling mainly...
-Took sparks out and cleaned them up (were full of black sooth, dry fooled)
-the car started a little bit easier and could mantain idle without stalling for around 30 seconds then began to stall (due to black sooth accumulating again on the plugs), plugs are not the problem.. something is fooling them up.
-Replaced them with new NKGs to rule out the plugs were fully fried, the same happened ran like 30 seconds "decently" then started to stall, took them out and swapped to old ones, not losing 60quid plugs like this!
-swapped lambdas upstream to downstream and viceversa, then back again... problem keeped the same.
I thought then...
-The ECU managed to f#%k up some injection adjustments by the unconstant combustion of running out of fuel.
-The timing belt got snapped one or two teeths and timing is not ok (retarded timing, thus overfueling)
-It has something to do with overfueling/air but how!!!
Some reading and renault diagrams inspection later, I thought of the knock sensor could got really nasty knock when running out of fuel and sent signal to the ECU wich retarded (a lot) the injection parameters, I bought a CAN Clip, since it was cheaper than taking it to a dealer. Managed to install the software and made some initial tests and scans on my car (just key on, but not running) and got some stored faults regarding the O2 sensors, one regarding the coilpack wich was disconnected, a faulty reading on the MAP (107MBAR Instead of 1070MBar that atmosphere reading should
be, and a fault 01DEF regarding the Throttle body... I will post a print screen later.
I connected the coilpack, cleaned and wiggled the connector of the MAP (wich resistance is ok 50K ohms) and all but one fault were gone. Yes, the TB fault still there, cleaned the connections checked the wires, cleaned the TB, and nothing.
I am now checking the throttle body ( 82 00 110 998 / 994 is the part no.) as the service manual says... there are six pins on the connector, 2&6 are the reference and earth of the two potentiometers, 1 & 4 are each the return signal of each of the redundant potentiometers and finally 3&5 are the command to the stepper motor of the throttle.
Resistance between 1&4 should be 1200ohm +- 400, between 6&4 1000 ohm +- 200 and between 2&4 not specified but I measured it and was 580 ohm. my lectures are 1650ohm (out of spec by 50ohm) 1220 ohm (out of spec 20 ohm) I am really not very worried about these values since could be the ohmmeter error.
I am now trying to put from zero to five volts on the stepper motor terminals 3&5, but I DO NOT KNOW THE MAX ALLOWED CURRENT on that!!! I don't want to fry the motor or will get in more troubles... I want to plot the potentiometer outputs vs the input voltage to the motor (or the rotation) and compare to the specified curves of the components
CAN PLEASE ANYONE HELPE ME TO GET:
- VOLTAGE NEEDED ON THE STEPPER ... IS IT 0-5V OR 6-12V???? OR...
- THE MAX CURRENT ALLOWED TO THE TB STEPPER MOTOR (terminals 3&5)
- THE RESISTIVE CURVES OF THE POTENTIOMETERS
(anyone with access to Dialogys)
Next steps after finishing this check are:
- To re-install the TB and run the diagnostic tool again to see if the fault is cleared.
- Take knock sensor and replace it, since there is no way to diagnose it apparently.
- Replace or pinpoint the MAP sensor.

THANKS!!! any help will be greatly appreciated.
 
Last edited:
  Clio 2 ph.2 - 172
Just an update folks...

- I decided ro test the potentiometers with a DC supply at 5v, plotted the two graphs and both look fine, I will post the plots later.
- I tested the stepper motor, I noticed it starts opening at ~4.8V and stays on whatever position is until the voltage drops to ~1.7V, for further information, the max current I registered was about 1.6A when moving from closed to max open, but the current when already open drops to ~1.2A constant.

I don't know if the throttle should open continually from 0.5 to 5V. The ECU must sent pulses to it 0 or 5V, opening or closing it a little bit every X ms to adjust the opening constantly... CAN SOMEBODY WITH INJECTION MANAGEMENT KNOWLEDGE CONFIRM THIS?

I'll keep updating this, I am decided to get to the bottom of this!!!
 


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