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1990 Chrysler TC by Maserati | Engine won't idle/stay running


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Hello everyone,

 

Intro

I am reaching out on this forum because my younger brother recently purchased a 1990 Chrysler TC by Maserati that is a sweet ride. The car ran great during the test drives, and he drove it a couple times per week for about two weeks before we encountered any issues. We are trying to work on this ourselves and learn as much as we can while do it. Any help and advice you could share with us is very appreciated, or if you have recommendations for another forum or place we should reach out. Thank you in advance!

 

Please let me know how I can clarify better or if there are tests you think I should run, which I will respond with the results of.

 

The current problem:

The engine will turn once, then shut off. It is nothing harsh (such as heavy shaking or clanking - it seems smooth) BUT will not stay running for any amount of time. The caveat to this is that, as long as the accelerator is pressed or throttle is activated right after we get it to turn, the engine will stay running, but it will stop running soon as we let off the throttle/gas. After doing this two or three times we start to smell gasoline. We do not see any leaks underneath or in the bay of the car.

 

Our current diagnosis:

The way this all started was that ~5 minutes into a drive the car shut down (sounded similar to how it dies when an alternator gives out, power steering fails, accelerator does not work, car shut off). After pulling it to the side of the road we noticed the "Low Oil Level" light on the left side of the dash came on. Because of these items, we thought it had to do with the oil pressure sensor. We replaced that and did not see a fix. We now think it is perhaps and electrical issue or bad sensor. If it isn't that, we will then look into at fuel lines/tank/pump. We are not sure what it could be.

 

What we have done so far:

We have since changed the oil and oil filter, as well as replaced the Oil Pressure Switch that connects in right next to the oil filter and tested the plug for connectivity with a multimeter (was good). After replacing this we had a new symptom of heavy clicking surrounding the engine. We juiced up the battery and it returned back to our original problem of a good engine turn/start but no idle/run. All fuses were tested for connectivity and look good (using multimeter). We tested as many connectors for sensors and they show connectivity or read for power using a multimeter when key is on for accessories(even though we barely know what we are testing sometimes). Battery reads about 11.5 volts. 

 

Notewe purchased a service manual so that we can see the sketches and specs, so we are just beginning to learn about that.

 

What our ideas are:

  • Is this fuel supply related? Because of the gasoline smell, we are guessing we might need to learn how to check fuel injectors, or even fuel pump/tank/lines. 
  • Is this air supply related? My reading shows that improper air intake could be the issue. The large hoses are in good condition and connections are also good. We are going to check these again anyway. 
  • Is this starter or ignition system related? We don't think this is starter motor or ignition switch related because the engine will actually turn and respond to throttle as described above. However, we don't know what we don't yet know. 

 

It is a mystery to us why the this happened. Nothing obvious pops out as the problem to us novices. Thank you for reading and we would appreciate your support in helping us learn and fix this. 

 

Thanks,

Quinn B.

Edited by qbero
Adding clarity (see edit history)
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A 1990 TC had 3 different engines, which do you have?   SOHC, DOHC or v6?  Which service manual did you purchase?  Don't waste your money on a Chilton manual.  There is a way to check the cars systems.  The light you referenced on the left side of the instrument cluster will flash if you turn the key on-off-on-off-on.  Either record or count the flashes. Do not start the car just turn the key to the ON position, then off then ON, then off, then ON and count flashes.

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2 hours ago, Garnet & Gold said:

A 1990 TC had 3 different engines, which do you have?   SOHC, DOHC or v6?  Which service manual did you purchase?  Don't waste your money on a Chilton manual.  There is a way to check the cars systems.  The light you referenced on the left side of the instrument cluster will flash if you turn the key on-off-on-off-on.  Either record or count the flashes. Do not start the car just turn the key to the ON position, then off then ON, then off, then ON and count flashes.

1990 Chrysler TC Maserati
3.0L 181CI V6 FI VIN: S
 
The light does not flash when the key is turned to the on position. 
 
I've attached a pic to this reply that shows the manual we got. It is not an exact match, but the free repair manuals that are online (chime website) are a match to the car.

Maserati TC Manual.webp

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Posted (edited)

Here is update #1:

 

(NOTE: the labels I am using for each relay below are based on the image that is attached here, because this image matches the format we have it).

 

We have tested the Fan Relay, Clutch A/C Cutoff Relay, and Auto Shutdown (ASD) Relay. The way we tested was by providing power to the relay with alligator clips on pins 85 and 86, then checking for ohms resistance and continuity on pins 30 and 87. The Fan Relay seemed to be shot and didn't work. The Clutch A/C Cutoff Relay is good. The ASD Relay had continuity and 0 ohms of resistance, but was intermittently showing between 0.5 and 1.3 ohms of resistance (multimeter set at 20M for ohms) along with continuity not being static but irregular in the same pattern (randomly between every 1-3 seconds it would do this). 

 

I can't see how the Fan Relay would be the problem, and the cover on the relay does not allow you to plug them in wrong so we are not sure. We do think the ASD relay should be looked at further. 

Edited by qbero (see edit history)
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Do the 'key dance' and you should at least get codes 12 and 55

 

The instructions are on page 8A-18 of your manual under "fault codes" section.

 

-I realize you said above that the light does not blink with the key on, but with the key dance method it should definitely blink out a numeric code even if there aren't any faults.

 

My 3.0 V6 doesn't exactly die or shut off but if I have all the accessories on the battery gauge can drop a lot, and if I give it some gas and let it fall back to idle it will definitely almost die. I just replaced my alternator and that wasn't the problem. Same thing though, if I'm sitting at 2000rpms I don't have any issues. I get fault code 41. Curious to see what you end up finding to be the cause, and I hope you post the solution here when you do find it.

Edited by TomServo (see edit history)
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On 8/1/2024 at 7:08 PM, TomServo said:

Do the 'key dance' and you should at least get codes 12 and 55

 

The instructions are on page 8A-18 of your manual under "fault codes" section.

 

-I realize you said above that the light does not blink with the key on, but with the key dance method it should definitely blink out a numeric code even if there aren't any faults.

 

My 3.0 V6 doesn't exactly die or shut off but if I have all the accessories on the battery gauge can drop a lot, and if I give it some gas and let it fall back to idle it will definitely almost die. I just replaced my alternator and that wasn't the problem. Same thing though, if I'm sitting at 2000rpms I don't have any issues. I get fault code 41. Curious to see what you end up finding to be the cause, and I hope you post the solution here when you do find it.

Hey TomServo, this was a very helpful comment and allowed me to understand the first comment.  I did the "key dance" and got code 12, followed by code 55.  To be more clear about the car running while throttling it, it's not that it runs functionally, just that the engine doesn't konk out when doing so. 

Also I will definitely stay active and post the solution here! Thanks again.

 

Quinn

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Posted (edited)
On 8/1/2024 at 3:46 PM, Garnet & Gold said:

A 1990 TC had 3 different engines, which do you have?   SOHC, DOHC or v6?  Which service manual did you purchase?  Don't waste your money on a Chilton manual.  There is a way to check the cars systems.  The light you referenced on the left side of the instrument cluster will flash if you turn the key on-off-on-off-on.  Either record or count the flashes. Do not start the car just turn the key to the ON position, then off then ON, then off, then ON and count flashes.

Hey G&G, I did the on-off-on-off-on and got code 12, followed by code 55.  I am trying to learn more here. I have also replied to your message once already with the make and model, along with the manual I used. Thanks for your interaction. I am continuing to diagnose. 

Edited by qbero (see edit history)
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Are you able to check the Throttle Body? There's a slight chance your Idle Air Control (IAC) valve is stuck in the closed position? If it doesn't open, the engine starves for air at idle and will just shut off. It would also have a very hard time starting if the IAC is stuck closed. The IAC goes out of play as soon as you step on the gas, obviously since you aren't idle anymore.

 

While you are in there, get some throttle body cleaner and clean some of the carbon buildup which will just be good to do in general.

 

The IAC does have its own fault code (25 I think?), but I think that is just for if it is getting power and may not be for if it is functioning properly. They are relatively cheap at $50 from a local store, or as low as $15 from Rockauto for a cheapo, and pretty easy to replace. Just don't strip the star headed mounting screws like I did!

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