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Discussion Starter · #1 · (Edited)
I just wrapped up a complete rebuild on a 95 vr4 and having idle issues. Bought it from the second owner who let it sit since 2008. I did not attempt to start it knowing fluids, fuel, and timing belt would present possible damage to the motor. After I hauled it home I pulled the motor, replaced everything including bearings, rings, hone, and a complete valve job along with proper machining work on block and heads. I dumped the 5 or so gallons of fuel that sat in the tank, thoroughly cleaned the tank and hanger assembly, replaced pump, strainer, and filter. I checked and repaired any vacuum leaks present, replaced all hoses for intercooler and cooling system. The timing belt is Gates, tensioner is Gates, and verified several times that it was in time before buttoning it up. The intake and exhaust camshafts are in their respective location along with the sprockets. No after market mods and all stock aside from the radiator. I've been lurking in the forums for a while and tested/ replaced the following:
TPS did not give 400mv-1000mv reading per procedure, replaced with new unit and clocked per procedure.

IAC valve was stuck extended and did not meet the 40om on across the board with a few 0 readings-Replaced with new unit.

MAF harness side read voltage across its pins as per other forums specs and did not make a difference unplugged while cranking.

Cam and crank sensor harness side tested good, rpm is displayed accurately, fuel and spark is present and is taken away with both unplugged. both sensors display reasonable 0-5v reading while turning motor over by hand.

Checked fuses and relays, fuel pump relay clicks when starting-not sure when it stalls, ECI fuse is good.

Coolant sensor reads a reasonable temp.

Starter fluid didn't help

I've put ATF into the cylinders with no major difference to idle.

Spark tested good before and after it stalls

Tried two different fuel pumps, on a Delphi now, and no start with it hotwired. With hotwired it will catch very low(300 or so) rpm but not enough to idle

It will start and stall immediately, and won't start unless I unplug the cam+crank sensor, turn it over for 10 seconds, then plug in the sensors before starting again.

Fuel pump hotwire test connector gave constant fuel supply but did not change idle. Fuel pressure gauge order waiting on arrival

Verified crank-cam timing and intake/exhaust camshaft location on each head again

Pulled ecm, sonic cleaned it, replaced three radial capacitors with no change to condition.
No CEL

Found a used ecu that was reported to be working and it did not change anything.

Unplugged ECS without change

Verified no major vacuum leaks with smoke tester on four different occasions.

Spark and injector pulse is present after stalling

Pulled egr and verified valve moves with appropriate vacuum and its incredibly clean as is.

Swapped injectors for oem known working- no change

Hotwired fuel pump per stealth316 instructions.


Without fuel hotwire:
 

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Lovbyts
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Sounds like its not getting enough fuel.
 

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93 NA ATX 3000gt DOHC
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The intake and exhaust camshafts are in their respective location along with the sprockets.
Were cam positions confirmed by letter stamped on hexagon section when reinstalled? If the intake/exhaust swapped that could cause the low vacuum problem and yes you should have vacuum until accelerating hard and boost kicks in. And no if everything else is correct, ring blowby will not cause pressure in intake manifold, just excess pressure in crankcase.



I've noticed the fuel pump test lead next to the battery shorts once I jumper positive post to it with the dead pump, and havent tried with new pump.
This indicates a problem if BLACK plastic test connector is one used, not the blue or tan connector, and pump should run whether switch is on or not. True short should blow the #12 fuse under dash, so hard to understand what makes you suspect a short.

I think the mfi relay is okay, it clicks but I'm having trouble finding a proper pinout/test procedure.
If you have spark and fuel as you claim when cranking the MFI relay has to be working, because neither would be present if both halves wasn't working. But I'm not sure how the pump is if it won't run from test connector :unsure:.
 

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Discussion Starter · #4 ·
I used the black test connector, and with the old pump that was dead, the jumper wire instantly started glowing. I haven't checked fuse #12 under dash recently, I did find two blown fuses for cigarette port and the other I forgot a few days ago when attempting to start. I haven't tested the new pump via the black test connector but I will to cross off that. When I disassembled the heads I marked and placed each cam for the head and location they came off of. The rear cams are 1000% in the correct spot, but I'll double check the fronts. I don't suspect cam placement unless a coworker thought it was funny to move them around without me knowing. I'm wondering if the fuel pump relay and/or resistor can cause this, I might try hotwiring the pump and see if it stays running
 

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........... The rear cams are 1000% in the correct spot, but I'll double check the fronts. I don't suspect cam placement unless a coworker thought it was funny to move them around without me knowing. I'm wondering if the fuel pump relay and/or resistor can cause this, I might try hotwiring the pump and see if it stays running
Coworker could have mixed them up without knowing since the locations in heads are reversed with the front and back bank heads. Since intake cam is closest to engine center and exhaust cams are fatherless from engine center of each bank, if they were install in heads with same pattern when heads were off engine then one bank would be wrong. The front bank can be easily confirmed without removing the valve cover, by turning engine until cam gear marks line up, then view cam lobe positions thru oil fill hole of valve cover. See bottom photos and explanation in below link from 3SX.com.
the fuel pump relay and/or resistor could cause low/high pressure at wrong time if not working correctly, but I wouldn’t expect it to cause symptoms you’re experiencing unless there’s a bad enough problem to completely eliminate all fuel pressure at some point. But if you use the black test connector to run pump, that completely by-passes the pump relay and resister, so if runs then but not when jumped to connector you’ll know the problem is either with those or pump halve of MFI relay.
 

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I'm sorry.
I would like to try to help, but that huge run on paragraph you wrote hurts my head.

Can you break down, one at a time, the issues and your attempts to correct.

Bob.
 
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Discussion Starter · #7 ·
Coworker could have mixed them up without knowing since the locations in heads are reversed with the front and back bank heads. Since intake cam is closest to engine center and exhaust cams are fatherless from engine center of each bank, if they were install in heads with same pattern when heads were off engine then one bank would be wrong. The front bank can be easily confirmed without removing the valve cover, by turning engine until cam gear marks line up, then view cam lobe positions thru oil fill hole of valve cover. See bottom photos and explanation in below link from 3SX.com.
the fuel pump relay and/or resistor could cause low/high pressure at wrong time if not working correctly, but I wouldn’t expect it to cause symptoms you’re experiencing unless there’s a bad enough problem to completely eliminate all fuel pressure at some point. But if you use the black test connector to run pump, that completely by-passes the pump relay and resister, so if runs then but not when jumped to connector you’ll know the problem is either with those or pump halve of MFI relay.
The fuel pump test lead certainly worked but did not get it running. I could hear the pump and fuel flowing and the only change was that the car would sputter and not start instead of start and stall.
Pulled the ECU and that's certainly rough(photo in post). Next step is an ECU and I'll go from there.
Verified cams are in correct locations
 

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Discussion Starter · #9 ·
Any idea why the previous owner stopped driving it in 2008? Could this be an old problem (i.e. failed sensor) or is it something related to the rebuild?
Previous owner claimed it was due to overheating and a cracked radiator. Assuming the worst upon teardown, I was surprised how clean the internals were and the bottom end components still within spec. Went ahead with new componenets and now chasing what wasn't brought up with the sale or aging bits and pieces
 

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Discussion Starter · #11 ·
updated tests and findings. I suspected fuel pressure but that not the case. I'll check that the new IAC isn't bunk but I'm running thin on ideas now
 

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I read it, then re-read it, but I still may have missed it. Have you tested the injectors? Not uncommon for them to go funny after sitting for so long.

Have you checked injector pulse?
 

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Discussion Starter · #13 ·
I read it, then re-read it, but I still may have missed it. Have you tested the injectors? Not uncommon for them to go funny after sitting for so long.

Have you checked injector pulse?
The only injector test I've done is listening to the front three wih a screw driver. They each make their click when they fire before and after it stalls
 

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.............. but I'm running thin on ideas now
Don't recall you trying to pull any retained codes from ECU, if you don't know how to pull/read them below is link for guidance on '94 & '95 year cars, by simply ground pin 1 of data link connector and then watching CEL light flashes with ignition turned to on.
 

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The only injector test I've done is listening to the front three wih a screw driver. They each make their click when they fire before and after it stalls
Pull the rail out, flip it upside down and wind the engine over, that'll let you "check" fuel pressure and check the spray pattern of the injectors.

Maybe disconnect the coils first.

And have a fire extinguisher handy.

And a bucket of water.

Will the engine run on starting fluid? Or fuel sprayed down the throttle body?
 

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Discussion Starter · #16 ·
Don't recall you trying to pull any retained codes from ECU, if you don't know how to pull/read them below is link for guidance on '94 & '95 year cars, by simply ground pin 1 of data link connector and then watching CEL light flashes with ignition turned to on.
I haven't pulled codes as the CEL hasn't been on. It does light up when I unplug the crank+cam sensors. I'll check incase there's stored that aren't shown with the light. I have tried starter fluid with no change.
 

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I'll check incase there's stored that aren't shown with the light.
Exactly as most are retained even after light is off, the only way to clear retained codes is disconnecting battery for maybe ~ 10 mins to be sure they've been removed. Point is to see what has popped up in past, hopefully to point in direction of possible cause of your stalling issue.

There could be more than one and will be shown one after the other and will repeat as long as ignition switch is in ON position. Unfortunately can’t rely on crank & cam senor codes 22 & 23 being a problem now since you intentional caused those. But can see if something shows other than 22 &23, might have to clear all codes and start over with starting and stalling to look for codes only triggered by normal engine process.
 

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Discussion Starter · #18 ·
Exactly as most are retained even after light is off, the only way to clear retained codes is disconnecting battery for maybe ~ 10 mins to be sure they've been removed. Point is to see what has popped up in past, hopefully to point in direction of possible cause of your stalling issue.

There could be more than one and will be shown one after the other and will repeat as long as ignition switch is in ON position. Unfortunately can’t rely on crank & cam senor codes 22 & 23 being a problem now since you intentional caused those. But can see if something shows other than 22 &23, might have to clear all codes and start over with starting and stalling to look for codes only triggered by normal engine process.
Just check codes... the CEL flashes at a constant rate that seems pretty quick without any major pauses in-between. It just keeping flashing as long as the ground is connected. I've seen on another forum that indicates no codes?
 

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.......... I've seen on another forum that indicates no codes?
That’s correct, when no codes are present it flashes at constant rate with no pauses, which is considered the normal state.

So no information gained from that. I do wonder though why there was no codes stored from when you disconnected the crank and cams sensors to test CEL indicator, unless battery has been disconnected for period of time since you did that.
 

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Discussion Starter · #20 ·
That’s correct, when no codes are present it flashes at constant rate with no pauses, which is considered the normal state.

So no information gained from that. I do wonder though why there was no codes stored from when you disconnected the crank and cams sensors to test CEL indicator, unless battery has been disconnected for period of time since you did that.
Right I did disconnect the battery before starting and reading codes
 
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