Hello
Please forgive me of wording/ language mistakes as i’m not native english speaker but hopefully enough to understand the issue.
Year ago I decided to refresh engine in new buyed 92’ corrado 2.0 16v [CIS-E Motronic]. Intention was to keep 100% ori car incl. 9A engine.
Point is that after whole works and some adjustments there is still problem with litlle shaking engine on idle and propably a bit to less RPM. Additionally ignition timing is adjusted a bit advance by ECU.
What was done:
- Complete overh. Of head, new timing belt etc.
- New knock sensor x2, new dizzy [aftermarket not Bosch], new leads, new sparkplugs, new temp. Sensor, new ISV
- Old fuel injectors mounted with new o-rings; new fuel filter; „fresh” fuel in tank
- TPS checked; working
- General cleaning all parts, no vacum leaks etc.
- Airflow sensor potentiometer checked and adjusted acc. To bentley manual [Input: 4,85v output fluctuate 0,75-0,81v]
- Mixture verified and adjusted using readings from Diff. Press. Regulator. Meassured current is fluctuating aprox. between 2 mA to 4 mA.
I’m using VCDS and OBD1 cable to connect with ECU and its working 😊 So, to adjust ignition timing I followed Bentley description- ECU was disactivated [by VCDS] and then I set using strobe lamp on proper mark on flywheel [6degree BTDC].
After all this adjustmens, engine:
- Starting without problems cold or hot
- RPM on cold is almost same as on hot. Acc. readings from ECU [vcds Read meas. Value block:3] is jumping between 816 and 888. In fact I do not feel difference with rpm on idle ; also rpm dashboard indicator is stable
- Ignition timing [ECU back to work when VCDS is off] is a bit advanced and is not stable- is jumping [visible when using strobe lamp]. Acc. to readings from VCDS [Read meas. Value block: 10] is jumping between +4.10 to +8,67. Average / most time is +7,27 what is aprox. equal to this what I can see by strobe lamp – most time is advanced [orginally is set +6]
- Propably due to above fact [jumping ignition] engine is shaking; additionally I feel that RPM is to low [despite of fact that ECU showing min. 818rpm].
- Engine is working quiet without any bad knocking or other strange sounds.
- Resistance of temp. sensor is giving readings aprox. +10degree more than in reality when engine is hot.
- Exhaust manifold temp. is about 250-290 C [idle running after ca. 10min].
On the begining when TPS was broken and ignition timing was continiuosly retarted by ECU -> temp. of manifold in short time exceed 350 degree and more so after 10min ex.manifold started to change colour to dark red :/
- Acc. to me smell of fuel from exhaust is a bit to rich but maybe I'm to sensitive ?;) ; catalysator on place.
Remain oxygen sensor to check but I do not have fault code from vcds [there is posibility to read faults if occur] and is no matter if hot or not -engine is shaking. Increasing RPM cause shaking disappear [aprox. From 1000rpm and up]
Does somebody meet with such a case? Whats more is worth to check ?
When car was buyed 1,5 y ago engine worked ok but from one hand idling was not so stable as now and was not so quiet but from other hand was no shaking problem
