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240 Hard Start, loping idle

It would explain the lack of voltage with KOEO at pin 13. Once I saw the high resistance, I had a feeling that was the root of the cause. I will check injectors when I return from the desert.
 
Hey all sorry for the blackout, in back from the desert a couple weeks now I ordered and he CT while I was there so that way it would be waiting for me when I got home sure enough that was definitely it. Now I just need to address the exhaust leak. And the phantom overdrive button issue.
 
Try plugging your old computer back in to see if it acts up. You may have just had some fretting or corossion on the terminals.
 
I have the same problem with my 1990 240. My car's been sitting at my local Volvo dealer for two weeks. They can't figure it out. After throttle body was cleaned and gasket replaced, new spark plugs, and new OEM injectors installed, issue still there. Few months before the issue, I replaced a faulty ECU (the one with a recall). Also, new ECT sensor and new fuel pumps. First time the issue appeared, it came with a check engine light on (Code 123). After cleaning the ground wire connectors on the intake manifold, issue was gone, the light too. After a couple of weeks cold start problem came back gradually, this time no check engine light. Any thoughts?
 
...cold start problem came back gradually...

Turn key to on position, listen for fuel pump to run...and before it quits, start engine.

Start Issue:

1. Got Fuel

and

2. Got Ignition

If you ain't got both, then start issues.

Since pumps were replaced, then FPR could be one potential issue...its bypassing fuel.
 
Replacing the FPR didn't help. Also, all connectors (ECU, EZK) were checked and cleaned. Voltage resistance on those looks fine too.
Someone suggested to unplug the cold start injector, no change. The mechanic gave up on it so I picked it up from the shop. He said the only thing he can think of is that the IAC might be bad. So I ordered one. I know it's a hit or miss, like everything I've done so far, but I have no choice.
 
RE: "...it will crank a couple seconds and then finally start, once it does, it acts like its going to die and the idle is rough and loping like a massive cam. "

I have higher lb injectors in 1993-245, and when cold starting, LH 2.4 "dumps" the fuel, so it runs rich, and I must elevate RPM for a minute or so, then O2 sensor informs LH 2.4 to back it down.

After reading thru, I'm wondering if your cold start injector is pissing away....only way to evaluate is to pull it out, and have it checked out, or via doing a pressure test, which may be a PIA for your vehicle.

As I indicated before, I took all injectors on a 1990 240 and had them cleaned/tested...iirc, fuel rail sits above cold start injector, so any debris in line could drop down into cold start injector. Also, cold start injector is used less in your climate.

Evaluating CTS at ECM's plug via ohm meter might be prudent.
 
RE: "...it will crank a couple seconds and then finally start, once it does, it acts like its going to die and the idle is rough and loping like a massive cam. "

I have higher lb injectors in 1993-245, and when cold starting, LH 2.4 "dumps" the fuel, so it runs rich, and I must elevate RPM for a minute or so, then O2 sensor informs LH 2.4 to back it down.

After reading thru, I'm wondering if your cold start injector is pissing away....only way to evaluate is to pull it out, and have it checked out, or via doing a pressure test, which may be a PIA for your vehicle.

As I indicated before, I took all injectors on a 1990 240 and had them cleaned/tested...iirc, fuel rail sits above cold start injector, so any debris in line could drop down into cold start injector. Also, cold start injector is used less in your climate.

Evaluating CTS at ECM's plug via ohm meter might be prudent.

I have new OEM injectors installed and unplugged the cold start injector.
 
Either do a

(1) fuel rail leak-down pressure test, or

(2) remove cold start injector and point into a bottle when activating fuel pumps.

Problem with test #1 is your FPR and Fuel Pump Check Valve (Bosch 1587010539) must be fit for duty.

Test #2 will be a PIA since parts will have to be removed on intake side to access and remove cold start injector.
 
Either do a

(1) fuel rail leak-down pressure test, or

(2) remove cold start injector and point into a bottle when activating fuel pumps.

Problem with test #1 is your FPR and Fuel Pump Check Valve (Bosch 1587010539) must be fit for duty.

Test #2 will be a PIA since parts will have to be removed on intake side to access and remove cold start injector.

The tech that worked on my car said he did test the cold start injector for leakage. Also just installed a new IAC, no change.
 
...he did test the cold start injector for leakage.

Really....

ECT - Engine Coolant Temperature

CTS - Catera Touring Sedan

Queue the cold nights/cool mornings, it will crank a couple seconds and then finally start, once it does, it acts like its going to die and the idle is rough and loping like a massive cam. If you don't give it gas fast it dies. Definitely not a fuel issue, can smell gas....It only does it on a cold start,

RE: "don't give it gas fast" - Give it more throttle-peddle pressure...this allows more air, not fuel. This means you have a rich mixture at idle.

ECT....When unplugged and engine started, does not exhibit original problems with loping, rough idle or acting like it was missing. Last edited by KeizerBrickGuy; 05-23-2019 at 09:40 AM.. Reason: Update

My LH 2.4 understanding is when ECT is disconnected, a default temp value is used... On the other hand, when plugged in, one has suggested it runs fine, once running and warmed up, which seems to be a contradiction here since when cold, your issue suggests additional fuel is being 'dumped' by injectors. I would not think wiring is the issue, and I have no idea what happens when an earlier ECT is bought, like say a 1984 Bosch ECT, which is different electrically.

I have this same issue as yours ("then finally start, once it does, it acts like its going to die and the idle is rough and loping like a massive cam") on my 1993-240, which has oversized injectors. But, after some 30 seconds of higher RPMs, I let throttle off, and its fine. Are you using stock injectors?

Time to scope it: https://www.youtube.com/watch?v=l4l25NfTyl8
 
But, after some 30 seconds of higher RPMs, I let throttle off, and its fine. Are you using stock injectors?

Yes, stock injectors. In my case, I don't have to hold the throttle pedal for it to run. Once it starts, it keeps running. Since yesterday though, rpms are not going back to normal, after a couple of minutes, like they used to. It idles at 1000 rpms, so I have to shut it off, restart the engine and then, it idles fine (750 rpms).
 
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