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01:33:44 - 12/20/2024
V8 Dakotas
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el_manaba
Dodge Dakota
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5/29/2007
20:08:54
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 Subject: Intake manifold gasket??
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I have a 96 Sport 4x4 with a 5.2L. The only significant mods I've done are: removed the catalytic converter, installed 3" exhaust with a Flowmaster, replaced downstream O2 sensor with a KatBox.
About 75% of the time, my engine idles really rough, sometimes to the point of dying. About 20% of the time, at full acceleration, the engine acts like it's missing on at least one cylinder. Occasionally, the engine won't even start unless I hold in the accerator about half way; I have to continue to hold it in for a few minutes during warm up. About 10% of the time at normal idle, the idle speed increases automatically by about 500 rpm for about 5-10 seconds; the engine speed sometimes increases automatically while driving at low speeds, especially in 4-low. Finally, my fuel efficiency is always below 10mpg. I seldom haul any load. The truck only has 75000 miles and doesn't consume any oil. I've recently replaced the plugs, wires, cap, rotor, and coil.
My check engine light frequently comes on and stays on for only 3 or 4 start cycles. I cycled the the keyswitch and counted the flashes to read the trouble codes. I looked up the codes in my Chilton manual: open or shorted condition in coil circuit, open or shorted condition in EVAP solenoid circuit, idle air control solenoid fault.
A took it to a local shop. First the guy told me to replace the EVAP solenoid, injector #7, and the PCV valve. I tested them all and found they were working fine. I told him to try again. He pulled his brother's Dak in alongside it and swapped out the components he suspected one by one. He finally concluded it must be a vacuum leak. He says that spraying some starting fluid around the base of the intake manifold evens out the idle temporarily, so I must have a bad intake manifold gasket.
I can believe that I have a vacuum leak. But I don't have all the classic symptoms of a bad intake manifold gasket. And that doesn't explain my other problems. Does anybody have any ideas on this? Anyone had any problems with the KatBox? Could it be a bad PCM?
Please help.
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OBIO3
Dodge Dakota
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5/29/2007
22:09:27
|  RE: Intake manifold gasket??
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You got multiple Problems. This is confusing your PCM. One thing you can bet on. The intake leak test your mechanic did is dependable. Just be sure there are no cracked hoses in the sprayed area and no missing vacuum connections or plugs. Fix the intake being VERY VERY SURE when you do, the fix is well done. You don't want it to still be leaking and screwing up your ongoing tests to discover other problems.
You never mentioned when all this started. Was it soon as you made your changes or at a much later date.
As far as your MODES go. You don't have any that help anything. My opinion. The exhaust pipe is to big with no significant HP increases. Bigger exhausts go with bigger intakes which go with increased HP so the engine can breath proper. . Removing the cat did nothing and I'm not sure what sensor you removed. I assume it was the one behind the cat. One thing for sure . Your going to discover 1 or more sensors that need replacing. You get the intake corrected, take the truck to a shop that has an obd tester. No auto zone stores here but we do have a checker auto and a couple other parts stores that will check a rig free of charge with a OBD. That should get you on the right track without spending money on things that are not busted. Good luck
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el_manaba
Dodge Dakota
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5/30/2007
11:37:32
| RE: Intake manifold gasket??
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Message:
Thanks for the prompt reply, OBIO3. In answer to your question, I didn't notice these problems immediately after I opened up the exhaust, but it wasn't too long after (a month or so) that the rough idle and poor fuel efficiency started.
The O2 sensor I replaced was downstream of the cat. I definitely agree that I won't realize any HP gains from my exhaust mods until I rework the intake. Anybody got any advice on intake mods? Shaved throttle body, cold air intake, drop-in K&N?
Also, I recently moved to California, so I'm gonna have to put a catalytic converter back in to pass smog tests. Does anyone have an opinion on high-flow cats? Anybody wanna buy a used KatBox?
Any tips on replacing the intake manifold gasket? What common pitfalls can I avoid?
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el_manaba
Dodge Dakota
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6/26/2007
01:08:16
| RE: Intake manifold gasket??
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Update: I replaced the intake manifold and plenum gaskets. There was evidence that both had been leaking. But I don't think that was nearly as serious as the other problem I discovered: the wires to the fuel injectors for cylinders 6 and 8 were swapped!! I don't know how long they had been that way. I'd looked at the left fuel rail because my PCM was blaming the problem on cylinder 7. But I'd never check the tags on the right fuel injector wires. The mechanic I took it to a few weeks ago claimed he pulled my fuel rail and swapped some injectors around, but it was apparent that he was lying about having done anything more than remove the air cleaner and spray some ether around. So I don't think he messed up my wires. Somebody has done some engine work on this truck before I bought it as evidenced by some jury-rigged stuff I ran across. So that's probably how the wired got crossed.
That brings me to my next point: I ordered a 3" catalytic converter from Magnaflow, got it welded in, and did the smog test. The smog guy said it passed emissions tests with flying colors except that he noticed that my 96 Dak (OBDII) had an EGR valve and that it had no regulator solenoid to allow the PCM to control it. He asked if I had replaced the engine with an older one because OBDII engines don't have EGR. He told me to just take it off and plug the holes and he'd pass it.
So apparently the morons who swapped my injector wires did so while swapping out the engine. They used an OBD engine. I assume they did not change the computer, so that's why the EGR regulator wasn't there. So, does anyone know what other differences there are between first and second generation OBD engines? Should I expect to have more problems due to this? Do I need to add/remove/swap any other sensors??
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gen1dak
Dodge Dakota
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6/28/2007
10:36:09
| RE: Intake manifold gasket??
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They could've used any Magnum engine (block). The EGR is in the intake and the exhaust. If they'd just replaced the block, they'd have had 1996 non-EGR intake/exhaust, so it sounds like they used a complete pre-'96 pull. The computer is most likely the correct one for the truck. Since it doesn't look for EGR, having it, and not being plugged into it isn't so much of an issue. Differences between the engines themselves are limited to external stuff, primarily the EGR and the fit of some of the wiring for some sensors, coil, etc differ slightly from OBDI, but the sensors themselves swap easily.
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miltonwaddums
Dodge Dakota
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8/10/2007
23:05:38
| RE: Intake manifold gasket??
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Wow man, someone did a number there. My advice is buy a throttle body for 96-99 318 (with an IAC) and swap the injector cables to their correct location (if havent already). I have a TB for this application for sale (but it lacks IAC solenoid).
This is all assuming that the PCM matches the truck, not the motor. If this is in fact the case, I would expect more problems from it. Gone are the glory days of carbs, mechanical distributors, and being able to run anything from an 8hp briggs to a 502 in any car you want.
If you already fixed this, I'd be interested to know what happened.
Jay
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