bad idle

All the beeping, zapping bits

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quest4power
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Location: Ocean City, MD

bad idle

Post by quest4power »

so here's the new rundown. i've got it to where i can start it on demand. it's just takes some skill to do so lol. it's similar to a blown charge pipe. the topic says bad idle...but really it's NO idle. but when i rev it up it runs pretty clean. but when i stop giving it gas it shuts off.

i'm running a rwd manifold w/ flange for egr delete. also running an N/A throttle body w/ isv delete. the intercooler and piping is brand, spank me in the ass, new. the motor is a 2.0 sohc wideblock w/ 1g rods/2g pistons and a 1g head. also, have not installed the radiator yet, so no coolant has been through the motor...coolant temp for the ecu is hooked up and resistance matches up with outside temp.

when i did the isv delete i tightened the BISS all the way down then backed it out about 2.5 turns...

anybody have any ideas...cause i'm stumped at this point

thanks to all who just read my epic novel above :wink:
quest4power
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Post by quest4power »

yeah. that was my next step. thanks man. i'm really happy with how the coil on plug set up came out too :wink:
75COLT
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Post by 75COLT »

Quest, is there black smoke coming from tail pipe or exhaust. does it only die on initial start up. need alittle more on whats happening with it.

Ian
1975 Dodge Colt GT/1968 Dodge dart
quest4power
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Post by quest4power »

it definately smells rich. i'm about to hook up the LM-1 and see just how rich. but like i said it dies when i let off the throttle. i haven't had it running for more than about 30 sec cause i haven't had the radiator hooked up. when i give it some gas it stumbles then clears up. symptoms are the exact same as a blown charge pipe
jeffball610
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Post by jeffball610 »

First I would check for boost leaks. A bad vacuum leak at idle will kill it and still let it run when you give it some juice.

Next I would look at the MAS. If you have a data logger (you should), then it can tell you if you are reading air flow. In the short time you've run the car, it may not throw a check engine light, but still be an issue.

I went through some issues recently with high idle that was caused by improper setup of the initial throttle body settings. Not directly related to what you're experiencing, but it may be worth a look. If you simply disconnect the throttle stop wire (single wire on throttle body) the ECU will think you're giving it some throttle and not go into idle mode. Start there. If setup properly, the throttle blade should be nearly closed (not sticking shut) and the TPS (throttle position sensor) should read 7% or so. Adjust the TPS to get a reading of 100% or near at full throttle and see what it reads at full closed after you set your throttle stop. This should get you close. After that, you need to set your idle using the data port ground and the under hood ground. This will tell the ECU you are setting idle and leave out its own adjustments.

After you have the idle set where you think it should be, you need to setup you timing. Make sure you set it up using the under hood ground wire so the ECU will not interfere. Then go back and set your idle again if needed.

I'm sure you've probably done this already, but may have skipped a step or overlooked something. The coolant may be an issue, but if the sensor itself is working, then the ECU should still run in normal mode. A bad sensor could lead to "limp mode" in the ECU map, but it should at least idle poorly instead of not at all.

Honestly, I think it's a boost/vacuum leak or MAS. You just don't seem to have enough air at idle, but still functions under throttle. Let us know if you figure it out, or eliminate at least one possible issue so we can focus in on the real issue(s).
quest4power
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Post by quest4power »

i set the tps using factory specs from alldata...it reads 5v at wide open and .4v or so at closed. i know it is not a boost leak...110%. on the i/c side of it anyway. brand new intercooler and piping...and for shits and giggles i did a leakdown test on the i/c system and confirmed its good. a bad vacuum leak is a possibility...but there's not a whole lot to my system. no emissions. 1 vac line to the heater controls, 1 to the brake booster, and one to my fpr and bov. like i said...i did the isv delete so the only thing the ecu should be adjusting during idle would be timing, correct?

i haven't had a chance to check it out yet...too busy with customer cars, and that comes before my own toys :wink:
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