L400 engine surges at 90km/hr

Have-dogs-needed-Van

Have-dogs-needed-Van

New Member
Just bought a 1999 L400 (auto diesel). Driving it home on the Highway realized the engine starts to "surge" while cruising around 90 km/hr. Doesn't seem to do this at any other speed or while accelerating.

The surging feels like the engine loosing power briefly and repeatedly , I have had a similar feeling from vehicles under acceleration that needed new spark plugs.

Any ideas where to start here?
 
I have just started to have a similar issue (94 L400 Diesel). Between 90-100 km/hr in D with O/D on the engine will kick down/up repeatedly, especially if there is a a slight incline. Mechanics at LinDen here in Golden, CO checked the vehicle and did not believe there was anything wrong with transmission or kickdown cable. They believed there was a loss of power causing the issue, possible fuel delivery or turbo related.
 
Managed to grab the codes, but will check transmission when I get a chance. I would say it doesn't feel like its changing gears repeatedly, but that could be my lack of experience showing.

It's also anytime the rpm is 2100-2300RPM I noticed, just harder to feel while accelerating.

I do have a few different codes here, more than I would like to have. Do these codes clear themselves after being resolved, maybe some are old?

13 Intake air temp sensor fault
14 Throttle position sensor (TPS) fault
21 Coolant temp sensor fault
22 Crankshaft position (CKP) sensor fault
25 Barometric (BARO) pressure sensor fault
 
Have-dogs-needed-Van said:
Managed to grab the codes, but will check transmission when I get a chance. I would say it doesn't feel like its changing gears repeatedly, but that could be my lack of experience showing.

It's also anytime the rpm is 2100-2300RPM I noticed, just harder to feel while accelerating.

I do have a few different codes here, more than I would like to have. Do these codes clear themselves after being resolved, maybe some are old?

13 Intake air temp sensor fault
14 Throttle position sensor (TPS) fault
21 Coolant temp sensor fault
22 Crankshaft position (CKP) sensor fault
25 Barometric (BARO) pressure sensor fault
Click to expand...
When grabbing the codes, how did you "Connect pin 1 to the metal chassis"? I saw that directive and wasn't 100% clear if I am just supposed to use a paperclip or ...
 
iboughtadelica said:
I have just started to have a similar issue (94 L400 Diesel). Between 90-100 km/hr in D with O/D on the engine will kick down/up repeatedly, especially if there is a a slight incline. Mechanics at LinDen here in Golden, CO checked the vehicle and did not believe there was anything wrong with transmission or kickdown cable. They believed there was a loss of power causing the issue, possible fuel delivery or turbo related.
Click to expand...
You need to check your Throttle Position Sensor (TPS). It probably just needs to be reset.
 
Have-dogs-needed-Van said:
Managed to grab the codes, but will check transmission when I get a chance. I would say it doesn't feel like its changing gears repeatedly, but that could be my lack of experience showing.

It's also anytime the rpm is 2100-2300RPM I noticed, just harder to feel while accelerating.

I do have a few different codes here, more than I would like to have. Do these codes clear themselves after being resolved, maybe some are old?

13 Intake air temp sensor fault
14 Throttle position sensor (TPS) fault
21 Coolant temp sensor fault
22 Crankshaft position (CKP) sensor fault
25 Barometric (BARO) pressure sensor fault
Click to expand...
This is probably a Series 2 L400 with the electronic injection pump. If you can check the TPS voltage while driving that may help narrow it down.
 
No smoke at all while driving. I think I also got the wrong descriptions for the blink codes. I've gone through some forums not really sure what codes are for a 1999 Charmix 4M40.

I've been a little distracted by a Alternator issue as well, no charging at low RPM and the battery/fuel water light come on at high RPM.
 
Have-dogs-needed-Van said:
No smoke at all while driving. I think I also got the wrong descriptions for the blink codes. I've gone through some forums not really sure what codes are for a 1999 Charmix 4M40.

I've been a little distracted by a Alternator issue as well, no charging at low RPM and the battery/fuel water light come on at high RPM.
Click to expand...
I strongly believe you need a specially made 120amp alternator.
 
Have-dogs-needed-Van said:
I've gone through some forums not really sure what codes are for a 1999 Charmix 4M40.
Click to expand...
Should be these:

JOBD diagnostics; error codes

Copied from delicaclub.ca: 1994+ Mitsubishi Diagnostic Trouble Code Retrieval Without Scan Tool Ground Data Link Connector terminal # 1. Pin4 and pin5 are ground so you can connect pin 1 and pin 4 with a paperclip or short wire (or use another ground point if preferred). Set the ignition...
delicaforum.com delicaforum.com
 
Still missing #22 under the 4M40 heading.
13. Atmospheric pressure sensor (Inbuilt within ECU).
14. Fuel temperature sensor.
21 Engine rotation sensor (Crank angle sensor).
22 Crankshaft position (CKP) sensor fault.??
25 Timer piston position sensor. (Within the fuel pump)
 
stevenlee said:






I strongly believe you need a specially made 120amp alternator.
Click to expand...
Midas in another town installed a rebuilt Alternator less than a year ago for the previous owner, they said the would maybe warranty depending on what Alternator. Can't see any label on the Alternator, not sure if its OG or not, and I don't want to drive all the way over to them just to have nothing done.

20230308_145644.jpg20230308_145306.jpg20230308_145529.jpg
 
Have-dogs-needed-Van said:
Still missing #22 under the 4M40 heading.
13. Atmospheric pressure sensor (Inbuilt within ECU).
14. Fuel temperature sensor.
21 Engine rotation sensor (Crank angle sensor).
22 Crankshaft position (CKP) sensor fault.??
25 Timer piston position sensor. (Within the fuel pump)
Click to expand...
Yeah, haven't ever seen 22 listed for a diesel anywhere...

Have-dogs-needed-Van said:
Can't see any label on the Alternator, not sure if its OG or not, and I don't want to drive all the way over to them just to have nothing done.
Click to expand...
Do they have record of what they put in? If not, they probably aren't going to be able to ID it either.
 
Update:

Had the Alternator replaced with a rebuilt unit, which the shops says has fixed the surging issue. Must have been dirty power to the fuel pump. That being said I didn't get any AC Voltage from a multimeter in that range of RPM. If you have problems with the alternator it may be best to check it with a oscilloscope if you have one, I am guessing I would have seen some funny stuff in the output of the Alternator. Could have also been a lack of power, but I didn't see a dip in Voltage during the performance issues.

All codes are also gone now.
 
You must log in or register to reply here.
Top