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I have a 90 bronco 5.8.I had a loss power and trans problems.for a little over a year.So I had a trans rebuilt with PATC TRANSMISSION parts and punisher valve body. Installed the trans and the truck still felt just as weak as it did before. If u stomp on the throttle it takes off good for a second but then power drops off till about 3500 then drops off again at about 4500rpm. So I checked the TPS sensor on a LAb scope and would get a erratic signal when u twist the wires.So I replaced it and felt a little better but still not right.I got a miss from 1500-1800rpm (which I always had) after that u don't feel as bad but still there.Did a KOER TEST and I get a code 18 so I replaced the distributor.Still no change and now trans wont shift at during the test drive after I installed the distributor. Set timing 10 degrees.Im like WTF is wrong with the truck.
What do u guys think??

here a list of thing Ive done in the past 3 years with 15K miles
O2 sensor
coolent temp sensor
fuel regulator
air temp sensor
new plugs
new wires
cap and rotor
rebuilt injectors

Super Moderator
26,007 Posts
yo fast,
18 KOER - SPOUT circuit open

18 Continuous Memory (CM) - IDM circuit failure or SPOUT circuit grounded.

KOER OK, so we can assume SPOUT is secure and good electrically; one test is to pull it & check it for 0 ohms; if NG, replace w/suitably sized copper wire

DTC 18 IDM circuit failure or SPOUT circuit grounded

Source: by Ford via Ben Watson in How to Tune and Modify Ford Fuel Injection via 18 ford&f=false

Ben doesn't mention that the wires leading to and from the SPOUT connector can ground or or are cut by the foil shield

Foil shield covers the wires to and from the Ignition Control Module (ICM) as well as the SPOUT circuit.

DTC 18 IDM circuit failure or SPOUT circuit grounded; "...The computer sends out a timing advance correction to the ICM over the SPOUT wire and then looks for the change on the IDM wire. You might check the ECT or the IAT sensor for your problem. Also check the SPOUT/IDM wire going to ground..."
Source: by DTC 18 or 212; Ignition Diagnostic Monitor (IDM) Troubleshooting; "...Identifying the correct module for your vehicle can be accomplished in a number of ways. First, always refer to the correct application in the Engine Management catalog. If that information is not available, check the wiring of the vehicle. If pin # 4 of the module gets a start signal (which should be battery voltage) from the starter circuit, it's a "Push Start" system. On the other hand, if pin #4 of the module is wired directly to pin #4 of the ECM, then it's a CCD system (refer to diagram #5)..." READ MUCH MORE Miesk5 NOTE; use BLACK CCD Ignition Modules in 94-96 Broncos Other years use the Gray Module
Source: by Joe D at

DTC 14 & 18; Profile Ignition Pickup (PIP) & Troubleshooting; "...The top three leads (for PIP signal) can lose continuity with the back plate (ground) on the module when the unit is hot. You should consider a remote mounted TFI. If your TFI is failing from heat, it can give off computer codes 14 (PIP) and 18 (SPOUT). stalling/dieing or sputtering when hot but runs when it cools off. This can be caused by a faulty TFI and the biggest culprits are heat. Another culprit can be a wire grounding out. Problematic TFI's can give off codes 14 (PIP) and 18 (SPOUT)..." read more

Thick Film Ignition (TFI) Troubleshooting Worksheet; miesk5 Note; this is the Grey Module
Source: by SeattleFSB (Seattle FSB) at

Ignition wiring diagram in your 90 Bronco 5.8; same as in Ford EVTM/PCED


Y/LG wires need to be checked
see more + TSBs @

I believe I have other info on the foil shield...some folks have found the foil shield has come in contact w/ckt.


I am posting this TSB in case someone mentions that there is a TSB out on Code 18;

DTC 18 in KOER TSB 87-24-17 in 88 Bronco, E & F Series 4.9L
Source: by Genco
DTC 18 in KOER
Source: by Genco at
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