Hyundai Excel 1990 EFI

Home  \  Repairs & Maintenance  \  Hyundai Excel 1990 EFI

The story so far....
Initially the car was starting to stall and lose all engine power, so my mechanical friend suggested I replace the fuel pump, so I did. The car ran fine for a bit, then the symptoms showed up again, stalling etcc. The car would re-start no worries, but once again, it would die in the arse. This only seemed to be happening when it got hot.
I then got a service station to run a diagnostic on the computer, which came back as telling me it was "Code 12", therefore it was the Mass Airflow Meter. I then purchase an airflow meter, fit it, drove off down the road and it goes and stalls again. I drive it back, the bloke at the shop let me try another airflow meter. Still no joy. I then drove the car, stalling about 5 times on the way, to another mechanic who had this all bells and whistles diagnostic machine. He hooked it up, ran the car for a good long while, but the only thing he could see that was wrong was the timing "BTDC" was low, around 4 degrees, instead of the normal, he reckoned, 10 degrees BTDC. So he has a look at the coil, sees some arcing/burn marks, and suggests I buy a coil. So I did, the car runs fine for ages, then the missus takes my son to daycare one day, and the bloody thing starts stalling again?!! I tell my original mechanical friend the problem, and he now suggests I look at the cars computer, ECU? It's costing a shitload, ideas please anyone? :banghead:

posted by  duncan

ugh heh i say buy a new car! :thumbs:
since your spending a grip in the first place might as well go with a new one

posted by  C c C

Yes, that would be the best idea! I would like to get the thing going first, before I try and sell it to some unsuspecting person, it a morals thing I have... :wink2:

posted by  duncan

on an efi model there is a mass air flow sensor and an ecm(computer)relay if the relay is going bad this would shut down the injectors/fuel pump and ecm and the air flow sensor also if the mass air flow sensor is going will give the ecm incorrect air flow and may make it stall
if you can try to find out what fails when it stalls you need fuel/spark/air
you know you have air getting into the engine so then it would be check the air flow sensor
will it stall at any speed or just at idle/stopping?

posted by  osborste

G'Day osborste, I had another look last night, removed the ecm, cleaned it up with some electroclean. The weird thing was, when I had the ecm removed, I managed to start the engine, and it seemed to run fine?!!
I shut it down straight away, then replaced the ecm after I cleaned it up, just a bit dusty, no apparent failure on any components. Started and ran the engine for about 20 minutes, all good. The trouble did start when it got hot, but when the missus went for a drive, it started stalling when it was fairly cold? The airflow meter is new, the dizzy cap is new, the leads and plugs seem fine, oh, and the fuel pump is new aswell. When I drove it, it was stalling whilst stopping, then when I could restart it, it seemed to stall again under load/acceleration. Then it would run fine for awhile, then die again. One thing I did last night, when it had been running for long enough to get some heat up, the engine fan came on as normal, I then disconnected the plug to the airflow meter, the engine chugged a bit, then kept going, but because the engine fan was running,(under a bit of extra load) when I reconnected the airflow meter, the engine stalled again. I did this a few times with the same result. Heat and a bit of extra load on the engine = stall?!!! Any ideas mate? :doh:

posted by  duncan

that car needs to be on ripley's believe it or not with the ecm unplugged there is no ground for the fuel injectors or distributor or ignition coil it should not have started at all
the only sensor that i can think of that would affect idle or letting off the gas to idle would be the idle speed control motor if its not working it could be jammed/dead in its lowest setting the car would have a hard time idling as the throttle plate would be closed
or the egr valve as it comes into operation once the engine is warm to hot
maybe sticking open or poor seal and flooding the intake with exhaust

the car doesn't have a remote starter control in it does it?

posted by  osborste

Bloody weird I know!! What is an egr valve? Definately no remote starter control in this puppy.... I just got off the phone with my mechanical friend, and he reckons that I may have fire-ants in the relays, I will check and clean all of them out 2nite, and post the results tomorrow. It certainly sounds plausible at the moment, our area is renowned for the little buggers!!!
Thanks for your thoughts. :thumbs:

posted by  duncan

it would seem you don't have an egr but a secondary a.i.r system similiar to an egr system (exhaust gas recirculation)
instead of and egr valve its a secondary air control valve

posted by  osborste

G'Day again, Thanks for the circuit diagram, I'll take it home and see what I can see. I looked over most of the relays I could find last night, definately no fire-ants, everything was fairly clean. What I did find underneath the dash, on the right hand side of the steering column was what looks to be an ECU, but I thought the only ECU was under the passenger seat?? I didn't have a go at taking this one out, I couldn't be stuffed at that stage...Any ideas what this one could be, it was the same width, but longer and had about three or four seperate plugs going into it from the bottom. The Missus hasn't been game to drive it yet, she probably doesn't trust my work!!!? It'll sit there and run at idle no worries, so far. Thanks again for your advice osborste. :thumbs:

posted by  duncan

Automatic Transaxle Control Unit (TACU) -is located under the left front seat.

Electronic Control Unit (ECU) -is located under the dash on the left side check the attachment
Relay Box -is located under the left side of the dash
it look like maybe you removed the wrong ecu(transaxle?)

posted by  osborste

hi duncan,

i want to share a bit of knowledge regarding your cars efi problem. since the trouble comes only when the engine is hot, the problem could be in the temperature sensors. most efi engines have 1 or 2 temp sensors. the sensors are located mostly in the intake manifold or if ever its not there just try to look for any sensors which are bolted into the engine and with 2 wires on it. the sensors can be checked though its resistance in ohms, so you'll need a multitester. when completely cold the resistance values are approximately 1400 to 1700 ohms and when hot(engine operating temp) the resistance drops to about 100 to 500 ohms. if ever temp sensors are good, try to replace the thermo-switch. this is a temp sensor but its function is to switch off the engine in cases of overheating( a sort of protection you know). hope this info could be of use to you. goodluck!

posted by  berwyn

You got it in one mate! It was the TACU that I checked first! No problems there, and the picture of the actual ECU is spot-on! I pulled that out on Friday, had a look, and noticed that the factory must have done a recall back in 1996, reading the sticker on the plate, then looking at the PCB, I could see that they replaced the capacitor located right in the centre, pretty dodgey looking job I might say aswell. Anyway, gave it a good hit with electroclean and put it back in. Went for a drive yesterday, ran fine all day, got to within spitting distance of our driveway, and she started playing up again. It was a very gradual stall, not straight away, I could tell that it was dying, I took my foot off the accelerator, and she slowy died. I could re-start it no worries, then it would stall again. After the third go, I gave it a bootfull, and managed to get it up into the driveway. I spoke with another mechanic this morning, and he said for me to check the output of the alternator, which I haven't done as yet, so I will tonight, other than that he said the ignition module could be at fault? So on it goes, and thanks again for your help osborste. :doh:

posted by  duncan

G'Day berwyn, when I check the resistance of these temp sensors, can I check them at the sensor end, or at the plug closest to the sensor?
When you mentioned the thermo-switch, is that the same thing as the thermostat, located on the inlet end of the coolant hose into the engine?
Thanks for your input.

posted by  duncan

hi duncan,

when you measure the resistance of the temp sensors you have to measure it at the sensor end, that is you have to detached or disconnect the electronic connectors. The thermo-switch is not the same as thermostat. Thermo-switch is an electronic device with connector on it, while thermostat is the mechanical device. In case you couldn't find the thermo-switch for now just check the temp sensors first. You should find two temp sensors in your case. hope this could help.

posted by  berwyn

I just deleted one message and two responses with quotes of a message containing racial slurs

It is OK to not like a particular make or model of a car or an an engine. It is OK to disagree with someone who posts a message. It is NOT OK to show no respect for a person, ethnic group etc. due to their race, religion, gender, etc.

posted by  tbaxleyjr

Other issues with these symptoms could be

1. distributor related issues (some imports have the cam shaft sensor built into the distributor assembly) or a transistor failing between the ECM and ignition coil or a bad ignition coil.

2. Bad fuel pump (but you said you replaced yours)

Someone mentioned this earlier - the next time the car is dead, check for spark and fuel to decide which path (fuel, spark, ecm) to chose when trouble shooting.

posted by  tbaxleyjr

Your Message