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Discussion Starter #1
I am just recently bought the 1990 spirit 2.5 l j I am trying to figure out the difference in between the two 2.5 l that were made that year and I am having a problem with break up at about 3000 RPMs it acts like it's missing can't really figure it out but I've fallen in love with this car I intended to give it to someone but I'm keeping it now help with anything is greatly appreciated
 

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Welcome To TD!!!

As far as diagnostics for your driveabilty issue...

1)Are there any fault codes stored in memory?
RETRIEVING FAULT CODES
https://www.turbododge.com/forums/f4/f14/362173-obd1-codes-retrieval-chrysler-1983-1995-a.html

If Yes, Post Back with the Code Numbers.

If No...
You need to start by checking basic ignition.
1)Verify the shutter wheel in the distributor is not loose.
IGNITION- Shutter Wheel And HEP.jpg
If loose either repair or replace the distributor.

2)Start the vehicle and perform a "wiggle test" on the HEP (Hall Effect Pickup) wiring and connectors.
Did the engine stall/stumble when wiggling the wiring connectors?
If yes when wiggling the wires replace the HEP.
If yes when wiggling/tugging the connectors repair the loose/corroded connector issue.

3)What do the spark plugs show?
The spark plugs are your eyes into what is happening in each cylinder.
Are the plugs fouled, worn/excessive gap, cracked/broken insulator, outside insulator covered with oil?
If the spark plugs are fouled, what type of fouling, post pics.
If worn replace the spark plugs.

SPARK PLUG CONDITION CHART
http://www.austincc.edu/wkibbe/plugchart.pdf

4)Verify the ignition system is capable of providing the proper KV for all driving/load conditions.
To do this you will need an "adjustable spark tester".
You need to verify that the system is capable of 25 KV Minimum at each cylinder.
If one or two cylinders are not capable of a minimum of 25 KV then the distributor cap/ignition wires may be at fault.
If All cylinders are not capable of a minimum of 25 KV then the ignition coil, coil secondary wire, rotor may be at fault.

ADJUSTABLE SPARK TESTER
https://www.autozone.com/test-scan-and-specialty-tools/ignition-tester/great-neck-adjustable-ignition-spark-tester/10257_0_0

IGNITION - Adjustable Spark Tester.jpg

If all of this checks OK you may want to replace the HEP with a "known good unit".
There is no real way to test the HEP for the driveabilty issue you are experiencing other than replacement.
(If HEP replacement is needed DO NOT place any sharp bends in the wiring as the factory had it or internal damage to the wiring will occur.)
HEP.jpg

Post Back with your results.
 

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Discussion Starter #5
I noticed the error in my first message I meant to say I have the 2.5 liter turbo j block new plugs new wires new cap I have checked all loose connections in a mission checked all injectors all injectors correctly firing check the timing the timing is correct now I'll start again when I start the car up everything runs fine at 3000 RPMs around the time that the Boost is supposed to be coming in which I can feel it in the rubber tube LOL starts to produce boost and I get heavy break up
 

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To answer to your PM, for what I remember they was a high torque version of the 2.5L turbo producing more torque :) mainly due to a different ECU (same mitsu turbo, no intercooler). It came with a stronger trans (A568).
 

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I noticed the error in my first message I meant to say I have the 2.5 liter turbo j block new plugs new wires new cap I have checked all loose connections in a mission checked all injectors all injectors correctly firing check the timing the timing is correct now I'll start again when I start the car up everything runs fine at 3000 RPMs around the time that the Boost is supposed to be coming in which I can feel it in the rubber tube LOL starts to produce boost and I get heavy break up
New does not always = good and new parts do not mean you do not have an issue in that circuit.system.
The system/circuit needs to be verified that it is functioning correctly before you can move to the next step of the diagnostic sequence.

If I were doing this in person it may only take a 1/2 hour to an hour to figure this out, however...
Online diagnostics are difficult at best.
I am not there with you, I can only guide you and I can only do that correctly/properly if I have accurate info available to me, not "I checked that" or "I replaced that".
If you decide to skip steps in the diagnostic sequence "assuming" the system is functioning properly rather than actually testing the system well then I think we are both wasting our time.

When I was a Diagnostic Specialist for Goodyear back in the 80's and ran into a problem I was having difficulty diagnosing and called the training center for assistance when they asked a question such as (example) "what was fuel pressure reading?" and I answered "it is good" or "I do not know" or "I did not check it yet" all you heard on the other end was a "click" as the phone hung up, they were not going to waste their time if I did not do my job properly so once again...

You are trying to diagnose a "Misfire" condition @ 3000 RPM's, not something that can be duplicated in the driveway or shop.
We/I cannot continue until we know 100% that the ignition system is not the cause of the issue.

1)Are there any fault codes stored in memory?
2)Is the shutter wheel loose in the distributor?
3)Did the engine stumble when performing a wiggle test on the HEP wiring?
4)Is the ignition system capable of producing a minimum of 25 KV at all 4 cylinders?
5)Are the plugs fouled or showing signs of fouling?
6)Are the plugs gapped properly?

Here is Chryslers Diagnostic Sequence for Driveabilty Issues Without Fault Codes.
The only tests listed that do not apply to your driveabilty issue are...
Tests NF-6A, NF-7A, NF-8A, NF-12A.
The NF tests for all other circuits/systems must actually be performed so each circuit can be verified OK and eliminated as the cause of your driveabilty issue.
As you can see Ignition is #1 on the list.

 
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