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dirty IAC ..vacuum leak... needs a tune up etc....
need more info... what have you done so far in trying to correct issue...??
 

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Discussion Starter #3 (Edited)
Ha, I didnt mean to post that, stoopid tablet app.....it was actually a long message, then I changed my mind as I have a couple of other ideas to try...

bUt as it posted it anyway I might aswell summarise...


Ran lovely in donor car, 88gt.

5.0 ho, explorer fuel rails and fpr fpr is new
Bosch 070 fuel pump - new
Stock everything else
Speed density setup
Removed thermactor and canp, no error codes apart from related to those
Tried blocking egr and unplugging it, capping vacs
Unplugged iac and set idle to keep it running warmed up
Unplugged o2 sensors to run from base tables
Did all 3 above at same time
No vac leaks
Tried iac restrictor
Tps is set correct
Set base idle
Ran without air filter
Ran with original ht leads
Timing with spout out is bang on 10
Cyls are all firing like clockwork.

Ive not yet checked the vacuum at idle

Im also wondering if running the map sensor sensors vac from a branching vac tee, with one of the thin pipes might give incorrect vac to the sensor... not sure what diameter pipe was used as stock, and what take off it used.. seems it was the large takeoff on the underside.. so I need to try that.

Its not a balance problem, I did have one, but sorted it.. it smooths off at higher revs.. and it vibrates errarically...

Cheers,

Mark
 

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Assuming you've done all the other checks (cracked plug, sticking valves, etc.), and you didn't do any other changes (like which plugs went to which injectors); then I'd plug the O2 sensors back in so it can try to run closed-loop. Right now, it should be running on 'limp-home' open-loop settings, which are kind-of crappy at-best. Open-loop is often worse than a carb, as it's not tuned to your specific engine and new installation, and it's just guessing how much fuel to squirt in there. Without some kind of feedback, it can't correct itself. Either tune your open-loop mode, or let it try to fix itself in closed-coop. Of course, tuning both would be best of all.

David
 

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Discussion Starter #5 (Edited)
Hi again :)

It doesnt idle well in closed or open loop, I just unplugged everything as a test.

Its not been out for a drive yet, I was wondering if it might just need more learning time ?

But right from cold it was super smooth when I took it out of the 88.

The plugs are new, new rotor and cap, new leads too, though I tried the old leads.

I used to drive it without the iac connected because the idle hung, though I have a new one fitted now.. but disconnecting it and setting it like it was doesnt help.

I have changed a few bits on the engine, it has a filter breather wher the oil filler used to go, still has pcv. I could try plugging pcv vac take off see if that changes things, not sure if I did that yet.

The map sensor isnt using the original vac line, I cant even remember what type of tube it used or what intake barb it connected to.. I think it was cobbled together, but clearly worked ok. I think the hose was a regular rubber one, not the nylon ones like I am using at present.

I dont have the second pink/blk wire connected in the fuel pump circuit, I didnt know where it went, and isnt in 88 diagrams.

I think I used an old coolant temp sensor as the one on the 88 was cracked around the connector, ive not tested this, I might replace it for good measure.

Im racking my brain to think of other things I might have changed...

What sensors are in use during warm up? Everything except the o2's ?
 

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What codes is it throwing now? Did you verify the distributor rotor's (shutter wheel) small tooth is approaching the sensor, when Cyl1 is approaching firing TDC (to sync the sequential properly)?

If you are making changes without erasing the ECM memory and DTCs, it can get even more confused. Make your changes, then clear the codes, then disconnect power and let rest to re-set. Start the engine, and let idle until fully warm, then do gentle driving, increasing in aggressiveness across 20-30 minutes. Stuff like a different exhaust will change flow through the engine, and therefore the tune required, though it should be able to auto-compensate within a limited range.

Also, unless you have a serious need to make changes, put it all back how it was when it was running good. EGR for example, is not a 'bad' emissions function, increases mileage, reduces part-throttle detonation, and does not affect high-power performance at all. The ECM only activates EGR during light-loads, such as cruise.

David
 

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Make sure you used the correct firing order for the cam you are using.
 

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Discussion Starter #8
What codes is it throwing now? Did you verify the distributor rotor's (shutter wheel) small tooth is approaching the sensor, when Cyl1 is approaching firing TDC (to sync the sequential properly)?

If you are making changes without erasing the ECM memory and DTCs, it can get even more confused. Make your changes, then clear the codes, then disconnect power and let rest to re-set. Start the engine, and let idle until fully warm, then do gentle driving, increasing in aggressiveness across 20-30 minutes. Stuff like a different exhaust will change flow through the engine, and therefore the tune required, though it should be able to auto-compensate within a limited range.

Also, unless you have a serious need to make changes, put it all back how it was when it was running good. EGR for example, is not a 'bad' emissions function, increases mileage, reduces part-throttle detonation, and does not affect high-power performance at all. The ECM only activates EGR during light-loads, such as cruise.

David
Hi there,

Pretty sure the stator / sensor is right, timing is bang on 10 woith spout out, the stator and rotor are linked and the sensor and cap too, so it should be fine, leads are allnon the right posts..

Egr is still on it, I only blocked it for a test.. only stuff thats gone is smog and canister stuff, fuel system is custom so cant put that back, as is breather... everything else is as close to stock as possible as its in a 68 mustang, so exhausts are similar with shorties, but theres no h pipe... mufflers are raptor turbo mifflers so nothing wild.

I'll grab the codes next time im at the garage, both the koer and koeo ones were only related to the missing thermactor and canister purge..

Ill go over a few things, double check, and do a full reset.. will report back.. :)

Cheers,

Mark.
 

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The codes are ...
OK, no 'bad' codes there, just for your thermactor air injection, EGR and vapor cannister purge (all missing). I forgot - what trans, and what idle vac do you get? I would also check and >meter test< the following grounds, as they are gremlins waiting to be released, and often cause idle issues:

Color/Pin#/Circuit
BLK/16/Ignition gnd
BLK/20/Case gnd
BLK-LGN/40/Pwr gnd
ORG/49/O2 gnd
BLK-LGN/60/Pwr gnd

David
 

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Discussion Starter #11 (Edited)
OK, no 'bad' codes there, just for your thermactor air injection, EGR and vapor cannister purge (all missing). I forgot - what trans, and what idle vac do you get? I would also check and >meter test< the following grounds, as they are gremlins waiting to be released, and often cause idle issues:

Color/Pin#/Circuit
BLK/16/Ignition gnd
BLK/20/Case gnd
BLK-LGN/40/Pwr gnd
ORG/49/O2 gnd
BLK-LGN/60/Pwr gnd

David
the grounds are all good

so the vac at idle is actually great, pretty stable around 21, but witha lttle shift around 1" either side of that with a bit oc idle variation....

I think for now im done chasing it... its not all thst bad, and its irregular, maybe itll clear up with some driving... if not ill start looking at the injdctors and things...

one last thing I wondered is if the duckbill connectors on my resevoir are the right diameter and the high pressure fuel pump inlet might be sucking a bit of air...

one thing that was happening, as an aside, my egr was pulling vacuum at idle, that wasnt the problem.. but im certain I had the vac solenoid hooked up the right way.

cheers,

mark
 

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I'd check all the plug wires for resistance, read the plugs again for any anomaly, look close at the EGR itself rather than just unhook its vacuum source to make sure its not sticking, then I would go to the intake manifold gasket.

It is very common on EFI 5.0s to receive a Printoseal gasket sometime during their life in the donor car and I have seen too many of them fail.

They run amazingly well even when one fails. No way of knowing if you have one of those in there, but for the afternoon it takes to swap a gasket, or if you KNOW there is a Printoseal in there already, that's where I would go.

One last thing, depending on how you fed the fuel rails, sometimes a damper can help, it sounds like you are running the factory setup, but if not I found a bit of tuning by adding a braided line between the banks and a damper on the end of the first rail.
 
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