Force India technical director Andy Green has revealed that the team's VJM11 is suffering from a 'fundamental underlying issue' which has undermined its performance so far.
The Silverstone-based outfit which has led F1's mid-field for the past two years has had a low-profile start to its campaign is hard at work to understand exactly why its 2018 pink charger has under-performed in the first two races of the season.
Green has undertaken a thorough review of all the collected data but has yet to identify the root cause its car's poor level of performance.
"It started probably between the Barcelona tests and Melbourne," the tech boss told Motorsport.com.
"We were a bit dubious about the data we were receiving, whether it was real or not, and then we needed to perform more tests on the car and some additional logging on the car, instrumentation, to see if it was a real phenomenon or not.
"Everything we have seen so far suggests it is real, so we have been attacking it to try to instigate a change. But as of yet we have yet to make any real inroads into it."
Without a clear understanding of its fundamental issue, Force India is also having to second guess the positive or negative impact of its recent updates, like the front wing that was tested in Bahrain last week.
"We are still very confident that the front wing does what we wanted of it," said Green.
"But it was designed to go with a car that generates more rear load which we don't have at the moment.
"Once that load appears and you put the wing on, that generates even more rear load so it is a double whammy. That is why we are very keen to break into it.
"It is incredibly difficult to judge [the potential of the car] because the tyres come into it massively. It is not just an aero load, it is a tyre management problem as well.
"It is very difficult to manage the rear tyres when you have a fluctuating rear load."
As it continues to work to come to grips with its issues, Force India expects a significant update scheduled for the Spanish Grand Prix to help alleviate its troubles.
"I am hoping we will have something that will attack it head-on Barcelona time," he said.
"There is definitely a solution there. What we are trying to do is find a quick solution.
"With a clean sheet of paper we could probably solve it straight away, but we don't have a clean sheet of paper, we already have a car that exists.
"So it takes a bit longer to try to do it with the resources we have and the car we already have. It will take a couple of races I think."
Despite the technical headwind, Sergio Perez was upbeat after finishing 11th fastest at the end of FP2 on Friday.
His team mate Esteban Ocon also reported no problems after setting the 13th fastest time in the afternoon.
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